Method and system for filtering a panoramic video signal using visual fixation

ABSTRACT

Methods and apparatus for filtering panoramic video signals using visual fixation are disclosed. A panoramic video signal organized into indexed frames is displayed and durations of visual fixations of a viewer of the display are measured by means of detecting the viewer&#39;s gaze positions and identifying clusters of adjacent gaze positions. For each visual fixation attaining a prescribed duration threshold, a segment of the panoramic video signal corresponding to a respective view region of prescribed shape and dimensions is extracted to form a filtered video signal. Contents of successive frames of the panoramic signal are cyclically supplied to a bank of content-filtering units operating concurrently to produce individual content-filtered frames which are concatenated for transmission to respective destinations.

CROSS-REFERENCE TO RELATED APPLICATIONS

The current application is a Continuation-in-Part of U.S. patent application Ser. No. 17/701,547 filed on Mar. 22, 2022, now U.S. Pat. No. 11,681,145 (VT-091-US-CIP1-CON), VT-091-US-CIP1-CON is a Continuation of U.S. patent application Ser. No. 16/908,592 filed on Jun. 22, 2020, now U.S. Pat. No. 11,287,653 (VT-091-US-CIP1), VT-091-US-CIP1 is a Continuation-in-Part of U.S. patent application Ser. No. 15/452,841 filed on Mar. 8, 2017, now a U.S. Pat. No. 10,694,249 (VT-091-US), VT-091-US claims benefit from U.S. provisional patent application 62/361,627 filed on Jul. 13, 2016 (VT-091-US-prov), and VT-091-US is a Continuation-in-Part of U.S. patent application Ser. No. 15/340,193 filed on Nov. 1, 2016, now U.S. Pat. No. 10,506,006 (VT-090-US). VT-090-US claims benefit from U.S. provisional patent application 62/249,599 filed on Nov. 2, 2015 (VT-090-US-prov), and VT-090-US is a Continuation-in-Part of U.S. patent application Ser. No. 15/259,962 filed on Sep. 8, 2016, now U.S. Pat. No. 10,419,770 (VT-089-US). VT-089-US claims benefit from U.S. provisional patent application 62/216,326 filed on Sep. 9, 2015 (VT-089-US-prov). The entire contents of all of the aforementioned applications and patents are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to broadcasting and/or streaming content-filtered multimedia signals of content selected from output of a panoramic signal source.

BACKGROUND

Current broadcasting methods of covering events exhibiting several activities are based on employing multiple cameras to capture activities taking place in different parts of a field of events. At any time, a person selects content captured by one of the cameras to broadcast.

The availability of panoramic cameras, each of which covering a view of a solid angle of up to 4π Steradians, motivates exploring alternate methods of covering such events.

Conventionally, streaming servers have been used to perform multimedia signal adaptation and distribution to individual client devices. With panoramic multimedia-signals, a high-capacity path need be established between the multimedia source and the streaming server, paths of adaptive capacities need be established between the streaming server and multiple client devices, and the streaming server need be equipped with powerful processing facilities. A streaming server may transmit multimedia data to multiple client devices. The server may perform transcoding functions to adapt data according to characteristics of client devices as well as to conditions of network paths from the server to the client devices. The multimedia data may represent video signals, audio signals, static images, and text.

Streaming multimedia data containing panoramic video signals require relatively higher capacity transport resources and more intensive processing. A panoramic video signal from a video source employing a panoramic camera occupies a relatively high bandwidth of a transmission medium. Sending the panoramic video signal directly from the video source to a client device requires a broadband path from the video source to the client's device and high-speed processing capability at the client device. Additionally, the video signal may require adaptation to suit differing characteristics of individual client devices.

In a panoramic-multimedia streaming system, it is desirable to provide clients with the capability to adaptively select view regions of panoramic scenes during a streaming session. It is, therefore, an object of the present invention to provide a flexible streaming server with the capability of client-specific signal-content filtering as well as signal processing to adapt signals to different types of client devices and to varying capacities of network paths to client devices. It is another object of the present invention to provide a method and a system for regulating data flow rate in a network hosting a streaming server. The system relies on a flexible streaming server with adaptive processing capability and adaptive network connectivity where the capacity of network paths to and from multimedia data sources, including panoramic video sources, and client devices may vary temporally and spatially.

SUMMARY

The availability of panoramic cameras, capable of capturing a near-spherical field of view, creates an opportunity to cover events taking place over a wide area and selectively broadcast and/or stream portions of the camera's output covering time-varying regions of interest. Realizing this feature requires means for dynamic determination of regions of interest and coordinating distribution of respective video signals to communication facilities. To address this challenge, the disclosed system forms:

-   -   (1) a panoramic multimedia source coupled to a panoramic camera         and including a unit for inserting a cyclic frame index within         encoded data of each video frame;     -   (2) a content controller, that can be located anywhere,         configured to receive the output of the panoramic multimedia         source and continuously produce frame-specific         operator-generated definitions of view regions of interest; and     -   (3) a view adaptor, that may also be located anywhere,         configured to receive the output of the panoramic multimedia         source and the operator-generated view-region definitions, match         individual view-region definitions with corresponding         video-frames content data taking into account receiving-time         discrepancy, and generate content-filtered video signals to         transmit to broadcasting stations and/or streaming servers.

In accordance with an aspect, the invention provides a method of video-content filtering for selective dissemination. The method comprises processes of:

-   -   (1) acquiring a panoramic signal organized into frames;     -   (2) generating a display of the panoramic signal;     -   (3) measuring durations of visual fixations of a viewer of the         display based on detecting the viewer's gaze positions; and     -   (4) for each visual fixation attaining a prescribed duration         threshold, determining a respective pivotal gaze position,         extracting a segment of the panoramic signal corresponding to a         view region surrounding the respective pivotal gaze position,         and transmitting the segment to an information-dissemination         facility.

A pivotal gaze position and a pivotal frame index are initialized as default values, and a gaze count is initialized to equal zero. The contour of the view region follows prescribed shape and dimensions.

An acquisition module receives a source signal from a panoramic signal source, detects a baseband signal from the source signal. and produces panoramic signal from the baseband signal. The baseband signal may be compressed and/or warped. The acquisition module may de-compress and/or de-warp the baseband signal where necessary. Additionally, if the detected baseband signal does not include frame indices, the acquisition module inserts a cyclical frame index into the content of each frame to produce frame-indexed content data.

Generating a display of the panoramic signal comprises supplying the panoramic signal to a virtual-reality headset configured to detect gaze positions of an operator wearing the virtual-reality headset. The headset is situated at a content controller. Measuring the duration of a visual fixation comprises processes of detecting gaze positions at regular time intervals and counting successive adjacent detected gaze positions where a pairwise displacement of any pair of gaze-positions is within a predefined proximity threshold.

Determining a pivotal gaze position comprises recurrently performing processes of:

-   -   (i) detecting a current gaze position of a current frame index;     -   (ii) evaluating a displacement of the current gaze position from         the pivotal gaze position; and     -   (iii) subject to establishing that the displacement exceeds a         prescribed proximity threshold, setting the pivotal gaze         position to equal the current gaze position, the pivotal frame         index to equal the current frame index, and the gaze count to         equal 1;     -   (iv) subject to establishing that the displacement does not         exceed the prescribed proximity threshold, increasing the gaze         count by unity; and     -   (v) where the gaze count equals a prescribed count threshold         extracting the segment based on the pivotal gaze position and         pivotal frame index.

At a view adaptor, a view boundary of the view region surrounding the respective pivotal gaze position is computed. To extract a segment of the panoramic signal corresponding to a view region, contents of successive frames of the panoramic signal are cyclically supplied to a plurality of content-filtering units, operating concurrently, to produce individual content-filtered frames according to the view boundary, so that each content-filtering unit processes one frame at a time. Individual content-filtering frames are cyclically concatenated for transmission to a designated destination.

Each content-filtering unit performs processes of retaining pixels within the view boundary of each frame of the successive frames to produce frame segments of interest. The frame segments are reframed, according to a specified frame format, to form the content-filtered frames. The content-filtered frames may be compressed prior to dissemination. The minimum number, N, of content filtering units is determined as a ratio of evaluated processing time per frame per content-filtering unit to a frame duration.

According to an implementation of the high-capacity view adaptor, where the view adaptor is collocated with the enhanced content controller, extracting frame segments comprises performing processes of:

-   -   (a) repeatedly receiving, from the acquisition module, the         frame-indexed content data of the panoramic signal and placing         the frame-indexed content data in a circular content buffer;     -   (b) repeatedly receiving, from the content controller, a pivotal         gaze position and a respective pivotal frame index then         directing the respective pivotal frame index to both a         view-region-definition module and a memory controller of the         circular content buffer;     -   (c) accessing the circular content buffer to read respective         content data corresponding to the respective frame index;     -   (d) receiving a view-region definition from the         view-region-definition module; and (e) supplying the respective         content data and view-region definition to a content filter.

The circular content buffer is provisioned to store frame content data extracted from the panoramic signal over a moving time window spanning an integer number, ϕ, of frames determined as: ϕ=(κ_(min)×ν)+1, where κ_(min) is a prescribed threshold of visual-fixation count κ, and ν being a predefined inter-gaze number of frames.

According to another implementation of the high-capacity view adaptor, where the view adaptor is distant from the enhanced content controller, acquiring a panoramic signal is performed at a first acquisition module collocated with the enhanced content controller and at a second acquisition module collocated with the high-capacity view adaptor. Each of the first acquisition module and the second acquisition module performs processes of:

-   -   (i) receiving, from a panoramic signal source, an enhanced         source signal based on indexed frames at source;     -   (ii) detecting a baseband signal from the enhanced source         signal; and     -   (iii) producing a panoramic signal, from the baseband signal,         the panoramic signal being frame-indexed.

Extracting frame segments at the high-capacity view adaptor comprises performing processes of:

-   -   (a) repeatedly receiving, from the second acquisition module,         frame-indexed content data and placing the frame-indexed content         data in a circular content buffer;     -   (b) repeatedly receiving, from the content controller, a pivotal         gaze position and a respective frame index and storing the         pivotal gaze position and respective frame index in a circular         control buffer;     -   (c) repeatedly sequentially reading from the circular control         buffer a pivotal gaze position and a respective frame index from         the circular control buffer and directing the respective frame         index to both of a view-region-definition module and a memory         controller of the circular content buffer;     -   (d) accessing the circular content buffer to read respective         content data corresponding to the respective frame index;     -   (e) receiving a view-region definition from the         view-region-definition module; and     -   (f) supplying the respective content data and view-region         definition to a content filter.

The circular content buffer is provisioned to store frame content data extracted from the panoramic signal over a moving time window spanning an integer number, Φ, of frames determined as:

Φ=┌(κ_(min)×ν)+((Δ₁+Δ₃−Δ₂)/f _(t))+1┐, wherein

-   -   κ_(min) is a prescribed threshold of visual-fixation count κ, ν         is a predefined inter-gaze number of frames, f_(t) is a frame         duration, Δ₁ is a transfer delay of the source signal from the         panoramic signal source to the content controller, Δ₂ is a         transfer delay of the source signal from the panoramic signal         source to the view adaptor, Δ₃ is a transfer delay of the         pivotal gaze positions from the content controller to the view         adaptor.

In accordance with another aspect, the invention provides a centralized apparatus for content-filtering of video signals. The apparatus comprises an acquisition module, a content controller, and a view adaptor.

The acquisition module is configured to receive a modulated carrier from a panoramic signal source and generate a baseband panoramic signal organized into indexed frames; The content controller comprises a device for producing a panoramic display of the baseband panoramic signal and a refresh module configured to measure durations of visual fixations of a viewer of the panoramic display, based on detecting the viewer's gaze positions. The refresh module determines a pivotal gaze position and a respective pivotal frame index for each visual fixation attaining a prescribed duration threshold;

The view adaptor comprises a module for computing a boundary of a view region, of prescribed shape and dimensions, surrounding the pivotal gaze position; and an array of content-filtering units operating concurrently to extract segments, corresponding to the view region, of specific frames of the baseband panoramic signal starting with a frame of the respective pivotal frame index and ending upon determining a new pivotal frame index of a subsequent pivotal gaze position.

The apparatus further comprises a circular content buffer holding content data of the baseband panoramic signal over a moving time window spanning a predefined number of frame periods, a first cyclical-access mechanism for sequentially transferring the specific frames of the baseband panoramic signal to individual content-filtering units of the array of content-filtering units, and a second cyclical-access mechanism for sequentially transferring the filtered frames to a respective destination.

The circular content buffer is provisioned to store frame content data extracted from the baseband panoramic signal over a moving time window spanning an integer number, ϕ, of frames determined as:

ϕ=(κ_(min)×ν)+1, wherein:

κ_(min) is a count of successive adjacent gaze positions within the prescribed duration threshold, where pairwise displacement of any pair of gaze-positions is within a predefined proximity threshold; and ν is a predefined inter-gaze number of frames.

In accordance with a further aspect, the invention provides a spatially distributed system for content-filtering of video signals. The system comprises a first acquisition module, a second acquisition module, a repeater, a content controller, and a view adaptor.

The first acquisition module is configured to receive a modulated carrier from a panoramic signal source and generate a baseband panoramic signal organized into indexed frames.

The repeater, collocated with the first acquisition module, retransmits the modulated carrier received at the first acquisition module to the second acquisition module to generate a replica of the baseband panoramic signal; The content controller, collocated with the first acquisition module, comprises a device for producing a panoramic display of the baseband panoramic signal and a refresh module configured to measure durations of visual fixations of a viewer of the panoramic display, based on detecting the viewer's gaze positions. The refresh module determines a pivotal gaze position and a respective pivotal frame index for each visual fixation attaining a prescribed duration threshold.

The view adaptor comprises a module for computing a boundary of a view region, of prescribed shape and dimensions, surrounding the pivotal gaze position, and an array of content-filtering units operating concurrently to extract segments, corresponding to the view region, of specific frames of the replica of the baseband panoramic signal starting with a frame of the respective pivotal frame index and ending upon determining a new pivotal frame index of a subsequent pivotal gaze position. The view adaptor further comprises:

-   -   (A) a circular content buffer holding content data of the         replica of the baseband panoramic signal over a moving time         window spanning a predefined number of frame periods;     -   (B) a first cyclical-access mechanism for sequentially         transferring the specific frames of the baseband panoramic         signal to individual content-filtering units of the array of         content-filtering units; and     -   (C) a second cyclical-access mechanism for sequentially         transferring the filtered frames to a respective destination.

The circular content buffer is provisioned to store frame content data extracted from the baseband panoramic signal over a moving time window spanning an integer number, ϕ*, of frames determined as:

ϕ*=┌(κ_(min)×ν)+(Δ₃−Δ₄)/f _(t))+1┐,

where κ_(min) denotes a count of successive adjacent gaze positions within the prescribed duration threshold, so that a pairwise displacement of any pair of gaze-positions is within a predefined proximity threshold, ν denotes a predefined inter-gaze number of frames, f_(t) denotes a frame duration, Δ₃ denotes a transfer delay of the pivotal gaze positions from the content controller to the view adaptor, and Δ₄ denotes a transfer delay from the repeater to the view adaptor.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be further described with reference to the accompanying exemplary drawings, in which:

FIG. 1 illustrates a system for panoramic multimedia streaming comprising a panoramic multimedia source and a universal streaming server, in accordance with an embodiment of the present invention;

FIG. 2 illustrates a system for panoramic multimedia streaming comprising multiple panoramic multimedia sources and multiple universal streaming servers, in accordance with an embodiment of the present invention;

FIG. 3 illustrates communication options between a panoramic multimedia source and a universal streaming server, in accordance with an embodiment of the present invention;

FIG. 4 illustrates communication paths corresponding to the communication options of FIG. 3 ;

FIG. 5 illustrates components of an end-to-end path corresponding to a first communication option of the communication options of FIG. 3 , in accordance with an embodiment of the present invention;

FIG. 6 illustrates components of an end-to-end path corresponding to a second communication option of the communication options of FIG. 3 , in accordance with an embodiment of the present invention;

FIG. 7 illustrates components of an end-to-end path corresponding to a third communication option of the communication options of FIG. 3 , in accordance with an embodiment of the present invention;

FIG. 8 illustrates components of an end-to-end path corresponding to a fourth communication option of the communication options of FIG. 3 , in accordance with an embodiment of the present invention;

FIG. 9 illustrates multimedia signals and control signals at input and output of a universal streaming server, in accordance with an embodiment of the present invention;

FIG. 10 illustrates components of an exemplary universal streaming server employing client-specific adaptation modules, in accordance with an embodiment of the present invention;

FIG. 11 details a client-specific adaptation module of the exemplary universal streaming server of FIG. 10 , in accordance with an embodiment of the present invention;

FIG. 12 illustrates temporal variation of flow rate of a compressed video signal;

FIG. 13 illustrates modules for generating video signals of reduced flow rates yet suitable for exhibiting panoramic full spatial coverage to enable a client to select a preferred partial-coverage view, in accordance with an embodiment of the present invention;

FIG. 14 illustrates a process of requesting and acquiring a content-filtered video signal, in accordance with an embodiment of the present invention;

FIG. 15 illustrates temporal flow-rate variation of video signals transmitted from a universal streaming server to a client device, the video signals including a frame-sampled video signal followed by a compressed video signal;

FIG. 16 illustrates the signal-editing module of FIG. 4 structured as a content-filtering stage and a signal-processing stage, in accordance with an embodiment of the present invention;

FIG. 17 illustrates the content-filtering stage of FIG. 16 implemented as an array of content filters for concurrent generation of different partial-content signals from a full-content signal, in accordance with an embodiment of the present invention;

FIG. 18 illustrates a signal-processing unit of the signal-processing stage of FIG. 16 ;

FIG. 19 illustrates the signal-editing module of FIG. 16 including details of the content-filtering stage and signal-processing stage, in accordance with an embodiment of the present invention;

FIG. 20 illustrates processes of video signal editing for a target client device, in accordance with an embodiment of the present invention;

FIG. 21 details a module for determining permissible flow rates;

FIG. 22 illustrates components of a client device, in accordance with an embodiment of the present invention;

FIG. 23 illustrates communication paths between a universal streaming server and panoramic multimedia sources in accordance with an embodiment of the present invention;

FIG. 24 illustrates communication paths between a universal streaming server and panoramic multimedia sources and communication paths between the universal streaming server and a plurality of heterogeneous client devices of a streaming system, in accordance with an embodiment of the present invention;

FIG. 25 illustrates communication paths between a universal streaming server and a multimedia signal source and communication paths between the universal streaming server and two client devices where an automaton associated with a client device may send commands to the universal streaming server, in accordance with an embodiment of the present invention;

FIG. 26 illustrates a modular structure of the universal streaming server, in accordance with an embodiment of the present invention;

FIG. 27 illustrates a learning module coupled to the universal streaming server of FIG. 26 , in accordance with an embodiment of the present invention;

FIG. 28 illustrates processes performed at a universal streaming server where a panoramic video signal is adapted to client-device types then content filtered, in accordance with an embodiment of the present invention;

FIG. 29 illustrates processes performed at universal streaming server where a panoramic video signal is content filtered then adapted to client-device types, in accordance with another embodiment of the present invention;

FIG. 30 is a flow chart depicting processes of acquisition of a panoramic multimedia signal and adapting the acquired multimedia signal to individual clients, in accordance with an embodiment of the present invention;

FIG. 31 is a flow chart depicting executing the processes of FIG. 30 in a different order, in accordance with another embodiment of the present invention;

FIG. 32 illustrates a streaming-control table maintained at the universal streaming server for a specific video-source, in accordance with an embodiment of the present invention;

FIG. 33 illustrates a process of initial adaptation of a multimedia signal for a specific client, in accordance with an embodiment of the present invention;

FIG. 34 illustrates a table recording a count of viewing-preference patterns for each type of client devices, in accordance with an embodiment of the present invention;

FIG. 35 illustrates processes of flow-rate control based on signal-content changes and performance metrics, in accordance with an embodiment of the present invention;

FIG. 36 illustrates a control system of a universal streaming server, in accordance with an embodiment of the present invention;

FIG. 37 illustrates a combined process of content filtering and flow-rate adaptation of a signal in the streaming system of FIG. 23 and FIG. 24 , in accordance with an embodiment of the present invention;

FIG. 38 illustrates a content filter of a universal streaming server, in accordance with an embodiment of the present invention;

FIG. 39 illustrates initial processes performed at the universal streaming server to start a streaming session, in accordance with an embodiment of the present invention;

FIG. 40 illustrates a method of adaptive modification of content and flow rate of a signal, in accordance with an embodiment of the present invention;

FIG. 41 illustrates criteria of determining a preferred encoding rate of a signal based on performance measurements pertinent to receiver condition and network-path condition, in accordance with an embodiment of the present invention;

FIG. 42 illustrates processes of determining a preferred encoding rate of a signal based on the criteria illustrated in FIG. 41 , in accordance with an embodiment of the present invention;

FIG. 43 illustrates a method of eliminating redundant processing of content selection in a universal streaming system serving numerous clients, in accordance with another embodiment of the present invention;

FIG. 44 illustrates transient concurrent content-filtering of a video signal to enable seamless transition from one view region to another, in accordance with another embodiment of the present invention;

FIG. 45 illustrates coupling the universal streaming server to a router-switch of a network, in accordance with an embodiment of the present invention;

FIG. 46 illustrates prior-art system for selective content broadcasting using multiple cameras, multiple displays, and a selector (switcher);

FIG. 47 illustrates an arrangement for broadcasting operator-defined content of multimedia signals in accordance with an embodiment of the present invention;

FIG. 48 illustrates a first system for combined broadcasting and streaming comprising a broadcasting subsystem and a streaming subsystem in accordance with an embodiment of the present invention;

FIG. 49 illustrates an acquisition module for extracting a pure multimedia signal, comprising a pure video signal and other multimedia components, from a modulated carrier signal received from a panoramic multimedia signal source in accordance with an embodiment of the present invention;

FIG. 50 illustrates an arrangement for content selection for broadcasting, in accordance with an embodiment of the present invention;

FIG. 51 illustrates a first broadcasting subsystem for selective content broadcasting employing a panoramic camera and a virtual reality (VR) headset, in accordance with an embodiment of the present invention;

FIG. 52 illustrates a geographically distributed system of selective video-content dissemination comprising a view adaptor and a distant VR headset, in accordance with an embodiment of the present invention;

FIG. 53 illustrates a view adaptor comprising a circular content-buffer, content filter, and a content-filter controller, in accordance with an embodiment of the present invention;

FIG. 54 details the view adaptor of FIG. 52 ;

FIG. 55 illustrates control data sent from the distant VR headset to the view adaptor of the system of FIG. 52 , in accordance with an embodiment of the present invention;

FIG. 56 illustrates data flow within the first system of operator-defined content of FIG. 47 ;

FIG. 57 illustrates data flow within the second system of operator-defined content of FIG. 52 ;

FIG. 58 illustrates control-data flow within the second system of operator-defined content for a case of large round-trip transfer delay between the view adaptor and the distant VR headset.

FIG. 59 illustrates determining a gaze position at a VR headset;

FIG. 60 illustrates updating content of the circular content buffer of the view adaptor of the broadcasting subsystem of FIG. 52 ;

FIG. 61 illustrates relating control data received from a distant VR headset to respective frame data, in accordance with an embodiment of the present invention;

FIG. 62 illustrates content of a circular buffer during successive frame periods, in accordance with an embodiment of the present invention;

FIG. 63 illustrates a method of generating operator-defined content using the distributed system of FIG. 52 , in accordance with an embodiment of the present invention;

FIG. 64 illustrates a method of adaptive content filtering based on changes of gaze position, in accordance with an embodiment of the present invention;

FIG. 65 illustrates a second system for combined selective content broadcasting and streaming employing a panoramic camera and a VR headset, the system comprising a muting facility and a distant content selector, in accordance with an embodiment of the present invention;

FIG. 66 details the routing facility of the system of FIG. 65 ;

FIG. 67 details the distant content selector of the system of FIG. 65 ;

FIG. 68 illustrates a hybrid system for selective content broadcasting using a panoramic camera, a bank of content filters, and a conventional switcher, in accordance with an embodiment of the present invention;

FIG. 69 is a flowchart depicting basic processes of the broadcasting subsystem of FIG. 51 ;

FIG. 70 is a flowchart depicting basic processes of the hybrid system of FIG. 59 ;

FIG. 71 is a flowchart depicting basic processes of the first system of FIG. 48 and FIG. 51 ;

FIG. 72 illustrates a method of content-filtering of a panoramic multimedia signal to produce an operator-defined content for broadcasting, in accordance with an embodiment of the present invention;

FIG. 73 illustrates processes performed at the remote content controller of the system of FIG. 65 , in accordance with an embodiment of the present invention;

FIG. 74 illustrates processes performed at view adaptor of the system of FIG. 65 , in accordance with an embodiment of the present invention.

FIG. 75 illustrates signal-transfer delays in a geographically distributed system of selective video-content dissemination;

FIG. 76 illustrates differences of arrival times of frame content data and corresponding control data at the video adaptor,

FIG. 77 illustrates effect of signal-transfer delay jitter on relative arrival times of frame content data and corresponding control data at the video adaptor and use of a circular control-buffer in addition to the circular-content buffer to overcome the effect of delay jitter, in accordance with an embodiment of the present invention;

FIG. 78 illustrates a view adaptor comprising a circular content-buffer, a circular-control-buffer, content filter, a content-filter controller, in accordance with an embodiment of the present invention;

FIG. 79 illustrates data-storage organization in a circular content-buffer and a circular control buffer for a case where the virtual-reality headset communicates control data every video-frame period;

FIG. 80 illustrates data-storage organization in a circular content-buffer and a circular control buffer for a case where the virtual-reality headset communicates control data every multiple frame periods;

FIG. 81 illustrates data-storage organization in a dual circular buffer clarifying matching frame control data and frame content data, in accordance with an embodiment of the present invention;

FIG. 82 illustrates a centralized content-filtering system, in accordance with an embodiment of the present invention;

FIG. 83 illustrates a spatially distributed content-filtering system, in accordance with an embodiment of the present invention;

FIG. 84 illustrates a method of identifying significant gaze positions and determining a visual-fixation measure, in accordance with an embodiment of the present invention;

FIG. 85 illustrates an example of detected gaze positions, for a case of sparse viewed positions (case-1), and identified visual fixation;

FIG. 86 illustrates selected view regions (view windows) for case-1 with a fixation threshold of 1 (κ_(min)=1);

FIG. 87 illustrates selected view regions (view windows) for case-1 a fixation threshold of 4 (κ_(min)=4);

FIG. 88 illustrates an example of detected gaze positions for a case of dense viewed positions (case-2);

FIG. 89 illustrates selected view regions (view windows) for case-2 with a fixation threshold of 5 (κ_(min)=5);

FIG. 90 illustrates identified clusters of gaze positions for another case of sparse view positions (case-3);

FIG. 91 illustrates reference gaze positions for case-3 with a fixation threshold of 1;

FIG. 92 illustrates reference gaze positions for case-3 with a fixation threshold greater than 1;

FIG. 93 illustrates indices of reference gaze positions for case-3 according to different criteria;

FIG. 94 illustrates timing of sending control messages from the refresh module of the content controller to the high-capacity view adaptor, in accordance with an embodiment of the present invention;

FIG. 95 illustrates identified clusters of gaze positions for another case of sparse view positions (case-4) with a fixation threshold of 5;

FIG. 96 illustrates control-data path from the content controller to the high-capacity view adaptor,

FIG. 97 illustrates timing discrepancy between control data and respective content data;

FIG. 98 illustrates propagation delay along a contention-free path from the content controller to the high-capacity view adaptor,

FIG. 99 illustrates transfer delay along a shared-network path from the content controller to the high-capacity view adaptor;

FIG. 100 illustrates a circular control-buffer used for locating frame contents stored in the circular content-buffer, in accordance with an embodiment of the present invention;

FIG. 101 illustrates contents of the circular content buffer and circular control buffer at a different observation time instant;

FIG. 102 illustrates a content filter implemented as a plurality of content-filtering units operating concurrently, in accordance with an embodiment of the present invention;

FIG. 103 illustrates processing durations of concurrent content filtering of successive frames, in accordance with an embodiment of the present invention;

FIG. 104 illustrates processed frames at separate content-filtering units;

FIG. 105 is a schematic of a high-capacity view adaptor receiving jitter-free content-control messages from the content controller, in accordance with an embodiment of the present invention;

FIG. 106 is a schematic of a high-capacity view adaptor employing a circular-control buffer to overcome delay jitter of content-control messages received from the content controller, in accordance with an embodiment of the present invention;

FIG. 107 illustrates timing of content-filtering for a single content-filtering unit;

FIG. 108 illustrates view-adaptation control of the view-adaptor of FIG. 105 , in accordance with an embodiment of the present invention;

FIG. 109 illustrates view-adaptation control of the view-adaptor of FIG. 106 , in accordance with an embodiment of the present invention;

FIG. 110 illustrates processes performed at a first device implementing high-capacity view adaptor, in accordance with an embodiment of the present invention;

FIG. 111 illustrates processes performed at a second device implementing high-capacity view adaptor, in accordance with an embodiment of the present invention;

FIG. 112 illustrates an alternate distributed content-filtering system, in accordance with an embodiment of the present invention;

FIG. 113 illustrates examples 1130 of temporal discrepancy between receiving of frame content data and receiving corresponding control data at the high-capacity view adaptor for the configurations of FIG. 112 ; and

FIG. 114 illustrates delays to be considering in determining the duration of a moving time window during which content data is held at the high-capacity view adaptor.

TERMINOLOGY

Geometric data: Data defining a selected view-region of a display of a video signal is herein referenced as “geometric data”. Frame: The term refers to a video frame of the video-signal component of a multimedia signal Gaze position: A point at which an operator of a virtual-reality headset is perceived to be looking is referenced herein as a “gaze position”. Generally, the gaze position may be represented as a set of parameters or a vector in a multidimensional space. In one implementation, a gaze position is defined according to conventional “pan, tilt, and zoom” parameters. Inter-gaze period: Gaze positions are detected at successive time instants of ν frame periods apart, ν>1. With ν=8, and a frame period of 20 milliseconds, for example, successive detected gaze positions are 0.16 seconds apart. Proximity threshold: A prescribed proximity threshold, denoted Δ*, is a prescribed distance between two gaze positions. A pair of gaze positions is said to be adjacent if the distance between them does not exceed Δ*. Visual fixation: The term refers to occurrence of successive adjacent gaze positions. Visual fixation is also referenced as “fixation”. Fixation-duration threshold: The term refers to duration of a number of adjacent gaze positions defining a significant observation. Visual-fixation count: The term, denoted κ, refers to a number of gaze positions within a distance from a reference gaze position not exceeding a prescribed proximity threshold Δ*. The number κ includes the reference gaze position. In FIG. 85 , for example, the visual-fixation counts with respect to clusters 8530A, 8530B, 8530C, and 8530D are 4, 5, 4, and 4, respectively. The visual-fixation count is also referenced as a “fixation count”. Fixation-duration threshold: The term refers to the duration of a prescribed visual-fixation count κ_(min), which is κ_(min)×ν frame durations, ν being an inter-gaze number of frames. For example, with κ_(min)=8, and 12 frames between successive gaze detections, the fixation-duration threshold is 96 frame durations. Insignificant gaze position: A gaze position having a number of adjacent gaze positions less than a prescribed count, is considered an “observation noise” and ignored. Naturally, it is desirable that κ_(min) be significantly larger than 1. Adjacent gaze positions: A first gaze positions is said to be adjacent to a second gaze position if the distance between the two positions does not exceed a predefined proximity threshold Δ*. Isolated gaze position: An isolated gaze position is a gaze position that does not have any adjacent gaze position. Pivotal gaze position: A pivotal gaze position is a gaze position having a number of adjacent gaze positions at least equal to a predefined count. In the case of FIG. 85 , the gaze positions detected at instants t₁, t₇, t₁₂, and t₁₆ are pivotal gaze positions. In the case of FIG. 95 , five clusters 9530A, 9530B, 9530C, 9530D, and 9530E of adjacent gaze positions, corresponding to reference gaze positions P₃, P₂₁, P₃₄, P₄₉, and P₆₃, are identified. Multimedia signal: A multimedia signal may comprise a video signal component, an audio signal component, a text, etc. Herein, the term multimedia signal refers to a signal which contains a video signal component and may contain signal components of other forms. All processes pertinent to a multimedia signal apply to the video signal component; processes—if any—applied to other signal components are not described in the present application. Signal: A data stream occupying a time window is herein referenced as a “signal”. The duration of the time window may vary from a few microseconds to several hours. Throughout the description, the term “signal” refers to a baseband signal. The term “transmitting a signal” over a network refers to a process of a signal modulating a carrier, such as an optical carrier, and transmitting the modulated carrier. The term “receiving a signal” from a network refers to a process of receiving and demodulating a modulated carrier to recover a modulating base band signal. Panoramic video signal: A video signal of an attainable coverage approximating full coverage is referenced as a panoramic video signal. The coverage of a panoramic video signal may exceed 27 steradians. Panoramic multimedia signal: A composite signal comprising audio signals, image signals, text signals, and a panoramic video signal is herein called a panoramic multimedia signal. Universal streaming server: A streaming server distributing panoramic multimedia signals with client-controlled content selection and flow-rate adaptation to receiver and network conditions is referenced as a “universal streaming server”. A universal streaming server may be referenced as a “server” for brevity. The server comprises at least one hardware processor and at least one memory device holding software instructions which cause the at least one processor to perform the functions of acquiring panoramic multimedia signals and generating client-specific content-filtered multimedia signals under flow control. Full-content signal: A multimedia signal may contain multiple components of different types, such as an encoded audio signal, an encoded video signal, a text, a still image, etc. Any component may be structured to contain multiple separable parts. For example, a panoramic video component of a panoramic signal may be divided into sub-components each covering a respective subtending solid angle of less than 4π steradians. Partial-content signal: The term refers to a signal derived from a full-content signal where at least one separable part of any component is filtered out and possibly other components are filtered out. Coverage of a video signal: The coverage (or spatial coverage) of a video signal is defined herein as the solid angle subtended by a space visible to a camera that produces the video signal. Full-coverage video signal: A video signal of coverage of 4π steradians is referenced as a full-coverage video signal. A full-coverage video signal may be a component of a full-content signal. Signal filtering: The term signal filtering refers to conventional operations performed at a signal receiver to eliminate or reduce signal degradation caused by noise and delay jitter; a signal-filtering process does not alter the content of the signal. Content filtering: The term refers to a process of modifying the information of a signal (following a process of signal filtering) to retain only specific information; content-filtering of a full-coverage (attainable coverage) video signal yields a partial-coverage video signal corresponding to a reduced (focused) view region. Full-coverage camera (or 4π camera): A camera producing a full-coverage video signal is herein referenced as a full-coverage camera or a 4π camera. Attainable-coverage video signal: A full-coverage video signal is produced by an ideal camera. The actual coverage of a video signal produced by a camera is referenced as the attainable coverage. Partial-coverage video signal: A video signal of coverage less than the attainable coverage is referenced as a partial-coverage video signal. A partial-coverage video signal may be a component of a partial-content signal. Partial-coverage multimedia signal: A composite signal comprising audio signals, image signals, text signals, and a partial-coverage video signal is herein called a partial-coverage multimedia signal. Source: A panoramic multimedia source comprises a full-coverage camera as well as de-warping and decompression modules; the term “source” is used herein to refer to a panoramic multimedia source. Raw video signal: The signal produced by a camera is referenced as a “raw video signal”. Corrected video signal: A de-warped raw video signal is referenced as a “corrected video signal”. Source video signal: A video signal received at a panoramic multimedia server from a panoramic multimedia source is referenced as a “source video signal”; a source video signal may be a raw video signal, corrected video signal, compressed video signal, or a compact video signal. Source multimedia signal: A multimedia signal received at a panoramic multimedia server from a panoramic multimedia source is referenced as a “source multimedia signal”; a source multimedia signal may contain a source video signal in addition to signals of other forms such as an audio signal or a text signal. Processor: The term “processor” used herein refers to at least one hardware (physical) processing device which is coupled to at least one memory device storing software instructions which cause the at least one hardware processing device to perform operations specified in the software instructions. Compression module: The term refers to a well-known device comprising a processor and a memory device storing software instructions which cause the processor to encode an initial video signal to produce a compressed video signal of a reduced bit rate in comparison with the bit rate resulting from direct encoding of the initial video signal. Decompression module: The term refers to a well-known device comprising a processor and a memory device storing software instructions which cause the processor to decompress a compressed video signal to produce a replica of an initial video signal from which the compressed video signal was generated. Source compression module: A compression module coupled to a video-signal source to generate a compressed video signal from a raw video signal, or from a de-warped video signal generated from the raw video signal, is a source compression module. Compression module 340 (FIGS. 3, 4, 7 , and 8) is a source compression module. Server compression module: A compression module coupled to a server to generate a compressed video signal from a source video signal video signal is herein referenced as a “server compression module”. Compression modules 1160 (FIG. 11 ), 1340, 1360 (FIG. 13 ), and 2030 (FIG. 20 ) are server compression modules. Server decompression module: A decompression module coupled to a server to generate a replica of a raw video signal or a replica of a de-warped video signal generated from the raw video signal, is herein referenced as a “server decompression module”. Decompression module 350 (FIGS. 3, 4, 7 , and 8) is a server decompression module. Client decompression module: A decompression module coupled to a client device to generate a replica of a pure video signal, or a content-filtered video signal, generated at a server, is herein referenced as a “client decompression module”. Compression module 2270 (FIG. 22 ) is a client decompression module. Compressed video signal: A compressed raw video signal is referenced as a “compressed video signal”. Compact video signal: A compressed corrected signal is referenced as a “compact video signal”. Rectified video signal: Processes of de-warping a raw video signal followed by compression, then decompression or processes of compressing a raw video signal followed by decompression and de-warping yield a rectified video signal. Pure video signal: A corrected video signal or a rectified video signal is referenced herein as a pure video signal. A pure video signal corresponds to a respective scene captured at source. Signal sample: The term refers to a video signal of full coverage (attainable coverage) derived from a pure video signal, or from a transcoded video signal derived from the pure video signal. The flow rate (bit rate) of a signal sample would be substantially lower than the flow rate of the video signal from which the signal sample is derived. A signal sample is sent to a client device to enable a viewer at the client device to select and identify a preferred view region. Encoder: An encoder may be an analogue to digital converter or a digital-to-digital transcoder. An encoder produces an encoded signal represented as a stream of bits. Encoding rate: The number of bits per unit time measured over a relatively short period of time is considered an “instantaneous” encoding rate during the measurement period. Rapid natural variation of the encoding rate may take place due to the nature of the encoded signal. A controller may force encoding-rate variation in response to time-varying conditions of a communication path through a network shared by numerous (uncoordinated) users. Forced encoding-rate variations are typically slower than spontaneous variations of the encoding rate. Flow rate: Without data loss, the flow rate of a signal along a path to destination equals the encoding rate of the signal at a server. Because of the natural fluctuations of the encoding rate, a parametric representation of the encoding rate may be specified by a user or determined at a controller. The parametric representation may be based on conjectured statistical distribution of naturally varying encoding rates. Metric: A metric is a single measure of a specific property or characteristic derived from sufficient performance measurements using, for example, regression analysis. Acceptance interval: A metric is considered to reflect a favourable condition if the value of the metric is bounded between a lower bound and an upper bound defining an “acceptance interval”. An acceptance interval is inclusive, i.e., it includes the values of the lower bound and the upper bound in addition to the values in between. Metric index: A metric may be defined to be in one of three states: a state of “−1” if the value of the metric is below the lower bound of a respective acceptance interval, a state of “1” if the value is above a higher bound of the acceptance interval, and a state “0” otherwise, i.e., if the value is within the acceptance interval including the lower and higher bounds. A metric index is the state of the metric. Transmitter: The term refers to the conventional device which modulates a carrier wave (an optical carrier or a microwave carrier) with a baseband signal to produce a modulated carrier. Receiver: The term refers to the conventional device which demodulates a modulated carrier to extract the transmitted baseband signal. Processor: The term refers to a hardware device (a physical processing device) Gb/s, Mb/s: Gigabits/second (10⁹ bits/second), Megabits/second (10⁶ bits/second)

The server of the present invention receives and disseminates panoramic multimedia signals. A panoramic multimedia signal contains a panoramic video signal in addition to signals of other forms, such as an audio signal and text. The description and the claimed subject mater focus on novel features relevant to the video-signal component. However, it is understood that the server delivers to client devices edited panoramic video signals together with signals of other types.

REFERENCE NUMERALS

-   -   100: System for streaming panoramic multimedia signals     -   110: Panoramic multimedia source     -   115: Transmission medium     -   120: Universal streaming server (referenced as a “server” for         brevity)     -   150: Network     -   180: Client device     -   200: Streaming system comprising multiple sources and multiple         servers     -   310: Panoramic 4π camera     -   312: Raw signal     -   320: De-warping module at server     -   322: Corrected signal     -   324: Rectified signal     -   330: De-warping module at source     -   340: Compression module     -   342: Compressed signal     -   343: Compact signal     -   350: Decompression module     -   352: Decompressed signal     -   420: Pure video signal     -   460: Signal-editing module     -   480: High-capacity path     -   490: Lower-capacity path     -   500: First communication path     -   520: Source transmitter     -   528: Modulated carrier signal to server     -   540: Server receiver     -   542: Baseband signal (warped)     -   560: Interfaces to client-devices     -   585: Modulated carrier signals to clients     -   600: Second communication path     -   628: Modulated carrier signal to server     -   642: Baseband signal (de-warped)     -   685: Modulated carrier signals to clients     -   700: Third communication path     -   720: Source transmitter     -   728: Modulated carrier signal to server     -   740: Server receiver     -   742: Baseband signal (warped, compressed)     -   785: Modulated carrier signals to clients     -   800: Fourth communication path     -   828: Modulated carrier signal to server     -   842: Baseband signal (de-warped, compressed)     -   885: Modulated carrier signals to clients     -   900: Source video signal (312, 322, 342, or 343)     -   905: Control data from panoramic multimedia source     -   925: Control data to panoramic multimedia source     -   935: Upstream control signals from client devices     -   940: Edited multimedia signals to client devices     -   945: Downstream control signals to client devices     -   1000: Components of a server     -   1005: All data from/to sources and client devices     -   1008: At least one dual link to network     -   1010: Server-network interface     -   1022: Source control-data module     -   1024: Source signal-processing module     -   1026: Client control-data module     -   1060: Client-specific adaptation module     -   1061: Client control bus     -   1090: Combiner of edited multimedia signals     -   1120: Content-filtering module; also called “content filter” for         brevity     -   1122: Content-filtered video signal     -   1132: Content-filtered transcoded video signal     -   1140: Transcoding module     -   1142: Transcoded content-filtered video signal     -   1152: Transcoded video signal     -   1160: Server compression module     -   1220: Mean bit rate     -   1225: Effective bit rate     -   1230: Specified peak bit rate     -   1300: Selective-viewing options     -   1320: Frame-sampling module     -   1322: Full-coverage frame-sampled signal     -   1340: Spatial-temporal server compression module     -   1342: Full-coverage compressed signal     -   1360: Spatial-temporal server compression module     -   1362: Succession of pre-selected content-filtered signals     -   1364: Succession of partial-coverage signals     -   1402: Message from client to server requesting server     -   1404: Message from client to server defining a selected view         region     -   1440: Compressed content-filtered video signal from server to         client     -   1520: Mean bit rate of compressed video signal     -   1525: Effective bit rate of compressed video signal     -   1600: Basic components of signal-editing module     -   1610: Content-filtering stage     -   1612: Selected content     -   1630: Signal-processing unit     -   1650: Conditioned multimedia signals to a set of client devices     -   1710: Server-network interface     -   1720: Content identifier     -   1725: Decompression module and/or de-warping module     -   1840: Transcoding module     -   1842: Signal adapted to a client device     -   1860: Flow-rate adaptation modules     -   1861: Buffer for holding a data block     -   1862: Memory device storing processor-executable instruction for         flow-rate adaptation     -   1900: Exemplary implementation of a signal-editing module     -   1922: Buffer for holding a data block of a content-filtered         signal     -   1923: memory device storing processor executable instructions         which cause a processor to modify the frame rate and/or         resolution     -   2000: Processes of video signal editing for a target client         device     -   2012: Identifier of a preferred view region     -   2014: Traffic-performance measurements     -   2016: Nominal frame rate and frame resolution     -   2030: Server compression module     -   2040: Module for determining a permissible flow rate as well as         a frame rate and frame resolution, compatible with a target         client device     -   2050: Transmitter     -   2052: Video signal together with accompanying multimedia signals         (such as audio signals and/or text) and control signals     -   2060: Network path     -   2110: Process of determining requisite flow rate at the display         device of the target client device     -   2120: process of determining a permissible flow rate (reference         2122) between the server and the target client device     -   2122: Permissible flow rate     -   2130: Process of determining requisite compression ratio     -   2140: Process of determining whether a compression ratio is         acceptable     -   2150: Module for determining a revised frame rate and or         resolution     -   2152: Revised frame rate and/or a revised resolution     -   2210: Memory device storing client-device characterizing data     -   2220: Memory device storing software instructions for         interacting with specific servers     -   2230: Client transmitter     -   2240: Client receiver     -   2242: Interface module     -   2250: Processor     -   2260: Memory device holding data blocks of incoming multimedia         data     -   2270: Client decompression module     -   2280: Memory for holding blocks of display data     -   2290: Display device     -   2314: Dual control path between a source 110 and a server 120     -   2412: Network path     -   2512: dual control path carrying control signals 905 from the         source 110 to the server 120 and control signals 925 from the         server 120 to the source 110     -   2525: multimedia payload signal path from a server 120 to a         client device 180     -   2526: Dual control path between a server 120 and a client device     -   2545: Automaton associated with a client device     -   2610: At least one hardware processor     -   2620: A set of modules devised to process a received panoramic         video signal 900     -   2621: Signal-filtering module     -   2640: Client-device related modules     -   2641: Client profile database     -   2642: Client-device characterization module     -   2643: Module for signal adaptation to client device     -   2651: Server-source interface     -   2652: Source characterization module     -   2660: Client-specific modules     -   2661: Server-client interface     -   2662: Module for signal adaptation to client environment     -   2663: Module for signal adaptation to client viewing preference     -   2725: Learning module     -   2820: Decompression modules and de-warping modules     -   2830: Module employing at least one respective hardware         processor for signal adaptation to client-device type     -   2925: Memory device storing predefined partial-coverage         definitions     -   2940: Module for signal adaptation to client's device     -   3010: Process of acquiring a panoramic multimedia signal from a         selected panoramic multimedia source     -   3012: Process of filtering a source video signal to offset         degradation caused by noise and delay jitter     -   3014: Process of decompression of a source video signal if the         signal has been compressed at source     -   3018: Process of video signal de-warping if the signal has not         been de-warped at source     -   3020: Process of receiving a service request from a client     -   3022: Process of adapting a pure video signal to characteristics         of a client's device     -   3026: Process of compressing a video signal adapted to         characteristics of a client device     -   3028: Process of signal transmission to a client device     -   3030: A control signal from the client specifying a preferred         view region     -   3032: Process of ascertaining viewing preference     -   3034: Process of content filtering     -   3000: Method of acquisition of a panoramic multimedia signal and         adapting the acquired multimedia signal to individual clients     -   3100: A variation of method 3000     -   3200: Streaming-control table     -   3300: Process of adaptation of a video-signal for a specific         client device     -   3310: Process of receiving from a client device a request for         service at client-interface module     -   3312: Process of identifying type of client device     -   3314: Process of determining prior identification of client         device     -   3316: Process of identifying an existing stream category         corresponding to a client device type     -   3320: Process of creating a new stream category for a new device         type     -   3322: Process of adapting a pure video signal to device type     -   3324: Process of recording new stream category     -   3326: Process of selecting an existing stream or creating a new         stream     -   3330: Process of signal transmission to a specific client device     -   3400: Table indicating a count of viewing options for each type         of client devices     -   3500: Processes of flow-rate control based on signal-content         changes and performance metrics     -   3510: Process of receiving performance measurements     -   3512: Process of computing performance metrics based on the         performance measurements     -   3514: Process of determining whether a current performance is         acceptable     -   3520: Process of receiving definition of a new content     -   3522: Process of filtering content of a pure video signal         according to received definition of the new content     -   3524: Process of determining flow-rate requirement corresponding         to the new content     -   3540: process of determining whether to enforce a current         permissible flow rate in signal encoding or to acquire a new         (higher) permissible flow rate from a network controller     -   3542: Process of enforcing a current flow rate     -   3544: Process of communicating with a network controller to         acquire an enhanced permissible flow rate     -   3550: Process of signal encoding under constraint of a         permissible flow rate (current or enhanced)     -   3600: Flow-control system of a universal streaming server     -   3610: Flow controller     -   3612: content-definition parameters (content selection         parameters)     -   3616: performance measurements     -   3625: Server-network interface     -   3630: Processor of a flow controller     -   3635: Module for determining a preferred flow rate (Module 3635         may implement processes 3500)     -   3650: Partial-content signal (content-filtered signal)     -   3640: Encoder of partial-content signal 3650     -   3660: Compressed signal transmitted to the client device     -   3700: Combined processes of content filtering and signal         flow-rate adaptation     -   3710: Process of receiving control data from client devices in         the form of content-definition parameters and performance         measurements.     -   3720: Process of examining content-definition parameters         received from a client device to determine whether         content-change is due     -   3730: Process of determining a preferred flow rate     -   3740: Process of determining whether a flow-rate change is         needed     -   3750: Process of communicating requisite flow rate to an encoder     -   3760: Process of communicating content-definition parameters to         content filter     -   3770: An imposed artificial delay to ensure that received         client's control data correspond to the changed signal content     -   3822: Processor dedicated to a content filter     -   3824: Software instructions causing processor 3822 to extract a         partial-content signal from a full-content signal     -   3826: Buffer holding blocks of full-content signals     -   3828: Buffer holding blocks of partial-content signals     -   3860: Updated content signal     -   3900: initial processes performed at a server to start a         streaming session     -   3910: Process of receiving a compressed full-content signal from         a signal source     -   3915: Process of decompressing the full-content signal to         recover the original signal generated at source     -   3920: Process of receiving a connection request from a client         device     -   3925: Process of determining whether connection request         specifies content-definition parameters     -   3930: Process of specifying default content-definition         parameters     -   3940: Process of extracting a partial-content signal based on         default content-definition parameters or specified         content-definition parameters     -   3950: Process of determining whether a flow rate for the         extracted signal is specified in the connection request     -   3955: Process of providing a default flow rate to an encoder     -   3960: Process of signal encoding at a specified flow rate     -   3970: Transmitting an encoded signal to a target client device     -   4000: A method of adaptive modification of content and flow rate         of an encoded signal     -   4010: Process of receiving content preference from an automaton         associated with a client device     -   4020: Process of determining whether content-change is requested     -   4030: Process of extracting a partial-content signal from the         full-content signal     -   4040: Process of signal encoding at a nominal encoding rate     -   4050: Process of determining encoding rate based on performance         data     -   4060: Process of encoding content-specific signal at a preferred         encoding rate     -   4070: Transmitting encoded content-specific flow-rate-controlled         signal to a target client device     -   4100: Criteria of determining a preferred encoding rate of a         signal     -   4110: Maintaining a current permissible flow rate     -   4120: Process of determining a permissible flow-rate based on         primary metrics     -   4130: Process of determining a permissible flow-rate based on         secondary metrics     -   4140: Process of determining a permissible flow-rate based on         primary metrics and secondary metrics     -   4210: Process of determining primary metrics based on         performance data relevant to a client's receiver     -   4220: Process of determining whether any primary metric is above         a respective acceptance interval     -   4225: Process of determining a reduced permissible flow rate         based on the primary metrics     -   4230: Process of determining a secondary metrics based on         performance data relevant to conditions of a network path from         the server to a client's device     -   4240: Process of determining whether any secondary metric is         above a respective acceptance interval     -   4245: Process of determining a reduced permissible flow rate         based on the secondary metrics     -   4250: Process of determining whether each primary metric is         below its predefined acceptance interval and each secondary         metric is below its predefined acceptance interval     -   4255: State of maintaining a current encoding rate     -   4260: Process of determining a new encoding rate based on the         primary and secondary metrics     -   4280: Process of communicating requisite encoding rate to a         respective encoder     -   4310: Process of receiving a full-content signal at a server     -   4320: Process of creating a register for holding parameters of         already extracted partial-content signals     -   4330: Process of receiving parameters defining partial-content         of the full-content signal from a specific client     -   4340: Process of examining the register to ascertain presence,         or otherwise, of a previously extracted partial-content signal     -   4350: Process of selecting either process 4360 or 4370     -   4360: Process of providing access to a matching partial-content         signal     -   4370: Process of extracting a new partial-content signal         according to new content-definition parameters     -   4380: Process of adding new content-definition parameters to the         register for future use     -   4390: Process of directing a partial-content signal an encoder     -   4420: Buffer holding data blocks generated by a signal-editing         module 460     -   4450: Multiplexer     -   4460: Multiple content-filtered streams     -   4540: A router-switch connecting to at least one server and/or         other router-switches     -   4541: An input port of a router-switch 4540     -   4542: An output port of a router-switch 4540     -   4600: Prior-art system for selective content broadcasting     -   4610: One of multiple signal sources each signal source         including a camera operator, a camera, and a communication         transmitter which may include an antenna or a cable access—a         signal source may be stationary or mobile     -   4612: A camera operator     -   4614: A camera     -   4616: A transmitter coupled to an antenna or cable access     -   4620: Transmission medium     -   4630: A receiver and decompression module with multiple output         channels at a broadcasting station     -   4640: Baseband signal, acquired from receiver 4630,         corresponding to a respective signal source 4610     -   4650: One of multiple display devices     -   4660: A content-selection unit for selecting one of baseband         signals fed to the display devices 4650     -   4662: An operator viewing the display screens 4650 to select a         corresponding baseband signal 4640     -   4664: Manually operated selector (switcher) for directing one of         the baseband signals produced at the output of the receiver 4630         to a transmitter     -   4680: Transmitter     -   4690: Channels to broadcasting stations and/or a Universal         Streaming Servers     -   4700: Arrangement for producing operator-defined multimedia         content for broadcasting     -   4710: Panoramic multimedia signal source     -   4712: Source signal (modulated carrier)     -   4714: Source processing unit     -   4715: Module for inserting in each frame data block a respective         cyclic frame number     -   4716: Source transmitter     -   4718: Transmission medium     -   4720: Acquisition module     -   4725: An operator wearing a virtual-reality (VR) headset to view         a panoramic display     -   4730: Pure multimedia baseband signal     -   4732: Signal descriptor     -   4740: Content selector for broadcasting     -   4750: Virtual-reality headset (VR headset) extracting, from a         pure multimedia signal 4730, a filtered signal corresponding to         operator's preferred angle of viewing     -   4752: Control signals between the VR headset and a         content-filter defining a view-region     -   4760: Content filter     -   4764: Content-filtered signal     -   4770: At least one panoramic-display device for received 4π         video signal     -   4800: First streaming and broadcasting system     -   4804: Broadcasting subsystem     -   4808: Streaming subsection     -   4810: Repeater; basically, an amplifier and physical (not         content) signal processing     -   4820: Streaming apparatus     -   4812: Transmission medium     -   4862: Compression module     -   4864: Compressed content-filtered signal     -   4870: Transmitter     -   4880: Channel to broadcasting station     -   4890: Channel to network 150     -   4940: Receiver     -   4943: Source multimedia signal     -   4946: Selector of a pure-signal generator 4950     -   4947: Output selector     -   4950: Pure-signal generators     -   5090: External display     -   5100: Broadcasting subsystem of system 4800 for selective         content broadcasting     -   5120: Monitoring facility     -   5200: Broadcasting subsystem for selective content broadcasting         using a view adaptor having a content buffer     -   5210: View adaptor     -   5220: Content-filter controller     -   5222: Frame identifier     -   5230: Content buffer (a circular buffer)     -   5240: Distant content selector     -   5250: Communication path to view adaptor     -   5260: Control signals from distant content selector 5240 to view         adaptor 5210     -   6000: Frame-data storage within circular content buffer 5330     -   6010: Frame-data blocks held in content buffer 5230     -   6020: Address of a frame data block in content buffer 5230     -   6500: A second system for combined selective content         broadcasting and streaming     -   6520: Routing facility     -   6522: Transmission channel from signal source 4710 to routing         facility 6520     -   6524: Transmission channel from routing facility 6520 to network         6530     -   6526: Transmission channel from network 6530 to routing facility         6520     -   6528: Transmission channel from routing facility 6520 to a         broadcasting station 6580     -   6530: Shared network (the Internet, for example)     -   6540: Remote content controller     -   6544: Channel from network 6530 to content controller     -   6546: Channel from distant content selector to network 6530     -   6548: Control data from the remote content controller 6540 to         the routing facility 6520     -   6551: Modulated carrier from routing facility 6520 directed to         distant content selector 6540 through network 6530     -   6552: Modulated carrier from routing facility 5520 directed to         server 120 through a cloud computing network 6570     -   6570: Cloud computing network     -   6580: Broadcasting station (Television Station)     -   6610: Repeater for carrier signal directed to server 120 and         distant content selector 5240     -   6670: Receiver     -   6710: Frame-number extraction module     -   6712: Frame-number insertion module     -   6720: Refresh module     -   6825: A bank of content filters 6832     -   6832: Content filter     -   6840: Baseband signal—output of a content filter 6832     -   6900: Method of selective content broadcasting relevant to the         system of FIG. 51     -   7000: Method of selective content broadcasting relevant to the         system of FIG. 68     -   7100: Method of combined broadcasting and streaming relevant to         the system of FIG. 47 .     -   7110: Process of receiving modulated carrier signal 4712 from         panoramic multimedia source 4710     -   7112: Process of acquiring a pure baseband multimedia signal         4730 (acquisition module 4720)     -   7114: Process of generating operator-defined content-filtered         multimedia signal     -   7120: Process of transmitting content-filtered signals to a         broadcasting facility and a Universal Streaming Server     -   7130: Process of relaying modulated carrier signal 4712 to         streaming subsystem     -   7140: Process of acquiring pure baseband multimedia signal 4730         at streaming subsystem     -   7142: Process of sending the full content of the pure multimedia         signal, at a reduced flow rate, to client devices accessing         Universal Streaming Server     -   7144: Process of receiving client-specific viewing preferences     -   7146: Produce content-filtered signals according to viewers         preferences     -   7148: Process of retaining operator-defined and viewers-defined         content-filtered signals for further use     -   7220: Process of receiving a source signal (a modulated carrier         signal) 4712 at content selector 4740     -   7230: Process of acquiring a pure baseband multimedia signal         4730 from the source signal     -   7240: Process of displaying a multimedia signal (including a         video-signal component)     -   7242: Process of initializing a gaze position as a null position     -   7244: Process of determining a current gaze position from an         output of a virtual-reality headset     -   7246: Process of determining a displacement of a current gaze         position from a reference gaze position     -   7248: Process of selecting a subsequent process (process 7250 or         process 7270) according to value of gaze-position displacement     -   7250: Process of updating a reference gaze position     -   7260: Process of generating and storing view-region definition         corresponding to a reference gaze position and a predefined         contour around the reference gaze position     -   7270: Process of extracting a content-filtered signal 4764 from         a pure multimedia signal 4730     -   7272: Process of compressing a content-filtered signal before         broadcasting     -   7274: Process of transmitting a content-filtered signal         (compressed or otherwise)     -   7280: Process of observing a subsequent gaze position and         repeating process 7244 to 7274     -   7300: Method of identifying clusters of gaze positions     -   7310: Process of receiving a source signal (a modulated carrier         signal) 4712 at distant content selector 5240     -   7320: Process of initializing a gaze position as a null position     -   7330: Process of acquiring a pure multimedia signal 4730 from         the source signal 4712 at distant content selector 5240     -   7340: Process of displaying a multimedia signal at distant         content selector 5240     -   7350: processes performed at Refresh module 6720 collocated with         distant content selector 5240 (FIG. 67 )     -   7352: Process of determining a cyclic frame number     -   7354: Process of determining a current gaze position from an         output of a virtual-reality headset of the distant content         selector 5240     -   7356: Process of determining a displacement of a current gaze         position 7354 from a reference gaze position     -   7358: Process of selecting a subsequent process (process 7370 or         process 7374) according to value of gaze-position displacement     -   7370: Process of updating a reference gaze position     -   7372: Process of forming a control message containing a frame         identifier and a reference gaze position     -   7374: Process of forming a control message containing a frame         identifier and a Null gaze position     -   7378: Process of transmitting the control message of process         7372 or 7374 to view adaptor 5210     -   7400: Processes performed at view adaptor 5210     -   7410: Process of receiving a new gaze position and a         corresponding frame identifier from distant content selector         5240     -   7412: Received frame identifier     -   7420: Process of determining an address of a frame data block in         content buffer 5230     -   7430: Process of reading a frame data block 5232     -   7440: Process of selecting process 7450 or process 7460     -   7450: Process of generating and storing view-region definition         based on new gaze position and a predefined region shape         (contour) at view adaptor 5210     -   7460: Process of generating a content-filtered signal 4764 based         on latest view-region definition when a control message includes         a null gaze position indicating change, or an insignificant         change, of gaze position     -   7462: Process of compressing a content-filtered signal at a         routing facility 6520 (FIG. 66 ) supporting the view adaptor         5210     -   7464: Process of transmitting the compressed content-filtered         signal from the routing facility     -   7480: Process of receiving a subsequent content-selection data         (new gaze position and frame identifier) from refresh module         6720 which is coupled to the distant content selector 5240     -   7500: A geographically distributed system of selective         video-content dissemination     -   7510: A path from a panoramic signal source to an acquisition         module     -   7512: Signal transfer delay along path 7510     -   7520: A path from the panoramic signal source to the acquisition         module     -   7522: Signal-transfer delay along path 7520     -   7530: A path from content selector 5240 to view adaptor 5210     -   7532: Signal transfer delay along path 7530     -   7550: A frame selector coupled to the panoramic signal source     -   7600: Discrepancy between arrival times of frame content data         and corresponding control data at the video adaptor     -   7620: Indices of frame-content data, example-1     -   7640: Indices of frame-control data, example-1     -   7660: Indices of frame-content data, example-2     -   7680: Indices of frame-control data, example-2     -   7700: Effect of signal-transfer delay jitter     -   7710: Case of no delay jitter     -   7720: Case of significant delay jitter     -   7730: Indices of frame-content data received at view adaptor     -   7740: Indices of frame-control data received at view adaptor     -   7750: Circular content buffer     -   7751: Cyclic frame index assigned at source     -   7752: Stored frame-content data     -   7761: Cyclic frame index received at view adaptor     -   7762: Stored control data     -   7800: Enhanced view adaptor     -   7822: Index of frame stored in circular-content buffer 7750     -   7900: Data-storage organization in the circular content-buffer         7750     -   7910: Divisions of the circular content buffer 7750     -   7920: Content data stored in a division 7910     -   7930: Divisions of the circular control buffer 7760     -   7940: Control data stored in a division 7930     -   7950: Cyclical access of the circular content buffer and the         circular control buffer     -   8000: Organization of the circular content-buffer 7750 and the         circular control buffer 7760 for the case if spaced sensing of         gaze positions     -   8030: Divisions of the circular control buffer 7760 with spaced         gaze-position sensing     -   8040: Control data stored in a division 8030     -   8100: Data-storage organization in a dual circular buffer     -   8120: Storage index of the circular content buffer     -   8122: Stored frame content data     -   8130: Storage index of the circular control buffer     -   8122: Stored frame control data     -   8200: Content-filtering system comprising collocated components     -   8202: A communication network     -   8204: A path from panoramic signal source 4710 to an acquisition         module of content-filtering apparatus 8250     -   8210: Enhanced content controller     -   8220: High-capacity view adaptor     -   8240: Channel from enhanced content controller 6210 to         high-capacity view adaptor 8220     -   8250: Content-filtering apparatus comprising collocated         acquisition module, enhanced content controller, and         high-capacity view adaptor     -   8260A: A baseband pure video signal detected from modulated         carrier 4712 received from panoramic signal source 4710     -   8260B: A replica of 8260A     -   8280: Signal compression and transmission unit     -   8290: Channels to broadcasting stations and/or universal         streaming servers     -   8300: Content-filtering system employing spatially spread         components     -   8304A: A channel from signal source 4710 to an acquisition         module 4720A collocated with the enhanced content controller         8210     -   8304B: A channel from signal source 4710 to an acquisition         module 4720B collocated with the high-capacity view adaptor 8220     -   8340: A dedicated path or a path through a network 8350C     -   8350A: A network to which both the panoramic signal source 270         and acquisition module 4720A connect     -   8350B: A network to which both the panoramic signal source 270         and acquisition module 4720B connect     -   8350C: A network to which both enhanced content controller 8210         and high-capacity view adaptor     -   8220 connect (networks 8350A, 8350B, and 8350C may be a same         network)     -   8360A: A local channel from acquisition-module 4720A to enhanced         content controller 8210     -   8360B: A local channel from acquisition-module 4720B to         high-capacity view adaptor 8220     -   8400: Method of content selection of a multimedia signal based         on visual fixation     -   8410: Process of receiving a source signal (a modulated carrier         signal) 4712 at enhanced content controller 8210     -   8420: Process of deriving a pure multimedia signal 4730 from the         source signal 4712     -   8430: Process of producing a display of a video-signal component         of a multimedia signal     -   8440: Process of initializing a reference gaze position as a         predetermined default position     -   8448: Initializing visual-fixation count κ     -   8450: Process of detecting gaze of a viewer of a display of a         video signal     -   8452: Process of determining a cyclic frame number corresponding         to a detected gaze position     -   8454: Process of determining a current gaze position     -   8456: Process of determining a displacement of a current gaze         position from a reference gaze position (also called a pivotal         gaze position)     -   8458: Process of selecting a subsequent process (process 8461 or         process 8462) according to value of a gaze-position displacement         from a reference gaze position     -   8460: Processes of regulating view-region updates     -   8461: Process of updating a reference gaze position     -   8462: Increasing visual-fixation count denoted κ (increasing the         count κ; κ←(κ+1))     -   8463: Resetting the visual-fixation count to equal 1 (κ←1)     -   8465: Comparison of visual-fixation count κ with a predetermined         threshold κ_(min);     -   8472: Process of forming a control message containing a frame         identifier and a reference gaze position     -   8478: Process of transmitting the control message to the         high-capacity view adaptor and revisiting process 8450     -   8500: Example-1 of tracking visual fixation     -   8510: Display area     -   8520: Default reference gaze position (initial gaze position)     -   8525: Reference gaze position (such as gaze positions 8525A,         8525B, etc.)     -   8530: A cluster of adjacent gaze positions (such as clusters         8530A, 8530B, etc.)     -   8540: An isolated gaze position (such as gaze positions 8540A,         8540B, etc.)     -   8600: Example-1, selected view regions (view windows) for a case         of a fixation threshold of 1 (κ_(min)=1)     -   8640: Reference gaze position     -   8650: View region (view window) surrounding a pivotal gaze         position     -   8670: Arrows indicating a sequence of defining the view regions         8650(2) to 8665(6)     -   8700: Example-1, selected view regions (view windows) for a case         of a fixation threshold>1 (κ_(min)=4)     -   8750: View region (view window)     -   8770: Arrows indicating a sequence of defining the view regions         8750(2) to 8750(4)     -   8800: Example-2 of tracking visual fixation     -   8810: An isolated gaze position     -   8820: An insignificant clusters of gaze positions     -   8830: A significant cluster of adjacent gaze positions     -   8900: Example-2, selected view regions (view windows) for a case         of a fixation threshold of 5 (κ_(min)=5)     -   8930: Reference gaze position (pivotal gaze position)     -   8950: A view region surrounding a reference gaze position     -   9000: Example-3 of tracking visual fixation     -   9005: Initialized reference gaze position     -   9010: An isolated gaze position     -   9030: A cluster of adjacent gaze position     -   9100: Example-3, reference gaze position for a case of fixation         threshold of 1 (κ_(min)=1)     -   9110: An isolated gaze position still used as a reference gaze         position     -   9130: A significant gaze position representing a cluster of         adjacent gaze positions     -   9200: Example-3, reference gaze position for a case of fixation         threshold exceeding 1 (κ_(min)>1)     -   9300: Example-3, indices of reference gaze positions according         to different criteria     -   9310: Case where a view region is defined for each detected gaze         position (κ_(min)=1)     -   9320: Case where a view region is defined for each cluster of         adjacent gaze positions and for each isolated gaze position     -   9321: Isolated gaze positions     -   9322: Clusters of gaze positions     -   9330: Case where a view region is defined only for clusters of         adjacent gaze positions     -   9332: Duration of a view region for case 9330     -   9400: Timing of sending control messages from the enhanced         content controller 8210     -   9410: Duration of a significant cluster of gaze positions     -   9420: Starting time of a significant cluster of gaze points     -   9421: Instant of reaching a predetermined fixation threshold     -   9422: Instant of receiving a last frame of the significant         cluster of gaze points     -   9430: Control message indicating start of a significant gaze         position     -   9460: Duration of a view region (view window)     -   9500: Example-4 of tracking visual fixation, reference gaze         position for a case of fixation threshold of 5 (κ_(min)=5)     -   9520: An insignificant cluster of gaze positions     -   9530: A significant cluster of gaze positions     -   9600: Control-data path from the enhanced content controller         8210 to the high-capacity view adaptor 8220     -   9620: Enhanced refresh module comprising a module for         determining visual fixation     -   9622: A dedicated path or a switched path through a network 9650     -   9642: Content-filtered data directed to other system components     -   9700: Temporal discrepancy between content data and         corresponding control data at the high-capacity view adaptor         8220     -   9720: Refresh-module delay     -   9740: Duration of a moving time window (which is also a storage         time window)     -   9800: Delay along a contention-free path from the enhanced         content controller 8210 to the high-capacity view adaptor 8220     -   9810: Control messages sent from the refresh module 9620 of the         enhanced content controller     -   9820: Control messages received at the high-capacity view         adaptor     -   9900: Delay along a shared-network path from the enhanced         content controller 8210 to the high-capacity view adaptor 8220     -   9920: Control messages, subjected to delay jitter, received at         the high-capacity view adaptor     -   10000: Content-data within a moving time window held in a         circular content buffer 10010     -   10010: Circular content buffer     -   10020: Sequential frame indices     -   10025: Frame content     -   10030: Detected gaze positions     -   10040: Circular control-buffer     -   10100: Content-data updates     -   10200: Content filter comprising multiple content-filtering         units 10240     -   10210: Baseband frame data     -   10212: Data defining view boundary of a frame     -   10220: Input port     -   10225: Content-filter selector     -   10230: Cyclical access to the content-filtering units     -   10240: A content-filtering unit     -   10250: A buffer holding content of a content-filtered frame     -   10255: Buffer selector     -   10260: Cyclical access to buffers 10250     -   10270: Output port     -   10280: A content-filtered frame to be sent to a destination (or         multiple destinations)     -   10300: Example of processing durations of concurrent content         filtering of successive frames     -   10310: Frame data received from an acquisition module     -   10311: Frame content data to be processed at a single         content-filtering unit 10240     -   10320: Received frame content data     -   10340: Filtered frame content data     -   10400: Processed frames at separate content-filtering units         10240     -   10410: A sequence of frames to be processed at a         content-filtering unit 10240     -   10420: A sequence of processed frames at output of a         content-filtering unit     -   10430: Filtered content data read from a buffer 10250 holding         output of a content-filtering unit     -   10500: A schematic of a high-capacity view adaptor 8220A     -   10510: A refresh-module interface     -   10520: A module for computing a view boundary surrounding a         reference gaze position;     -   10525: A (logical) on-off switch     -   10530: A memory device holding time-varying view boundary     -   10540: A (logical) combiner     -   10600: A schematic of a high-capacity view adaptor 8220B     -   10700: Timing of content-filtering processes for a single         content-filtering unit 10240     -   10710: Stream of successive reference gaze positions     -   10712: Individual reference gaze positions     -   10714: Computing time δ_(c) of producing a view-region boundary         for a reference gaze position     -   10720: Stream of computed boundaries of view regions     -   10722: An individual boundary of a view region     -   10724: Memory-access time interval δ_(a)     -   10730: Process of forming filtered frame content at a         content-filtering unit 1024     -   10732: Extracted pixels from baseband pure video signal within a         boundary 10722     -   10800: Device implementing high-capacity view adaptor 8220A         (FIG. 105 )     -   10810: Coordination module     -   10820: Processor (or an assembly of processors)     -   10830: Acquisition-module interface     -   10850: Interface to bank of content-filtering units     -   10900: Device implementing high-capacity view adaptor 8220B         (FIG. 106 )     -   10910: Coordination module     -   11000: Processes performed at the device of FIG. 108     -   11100: Processes performed at the device of FIG. 109     -   11200: Alternate distributed content-filtering system     -   11220: A repeater     -   11240: A path from repeater 1220 to acquisition module 4720B     -   11300: Control-data latency     -   11340: Duration of storage window     -   11400: Illustration of transfer delays

DETAILED DESCRIPTION

A conventional streaming server performs multimedia signal adaptation and distribution to individual client devices. With panoramic multimedia-signals, a high-capacity path need be established between the multimedia source and the streaming server, and paths of adaptive capacities need be established between the streaming server and multiple client devices.

The streaming server may acquire performance metrics of a connection between the streaming server and a client device and adjust the flow rate allocated to the connection according to the performance metrics. If the connection is allocated a guaranteed constant flow rate, for example through a dedicated link or reserved capacity of a network path, the performance metrics would depend on the value of the constant flow rate and the characteristics of the client device. If the connection is allocated a nominal flow rate, for example through shared links of a network, the performance metrics would depend on the value of the nominal flow rate, the fluctuation of the intensity of network data traffic from other data sources, and the characteristics of the client device.

The streaming server may also be configured to process a signal received from a panoramic multimedia source to derive signals of partial content. The streaming server of the present invention may receive a signal from a source containing a full coverage panoramic video signal covering a solid angle of 4π steradians and derive a signal of partial coverage. With such capability, a person viewing a display of the video signal may select, using an input device, a specific partial coverage according to the person's viewing preference. The information content of the preferred video signal depends largely on the selected coverage. Thus, the performance metrics would depend on the value of the nominal flow rate, the fluctuation of the intensity of network data traffic from other data sources, the characteristics of the client device, and the selected information content.

Instead of specifying a nominal flow rate, a viewer may specify a fidelity level and information content. The multimedia server may translate the fidelity level into a requisite flow rate.

A streaming server providing both content selection and flow-rate adaptation to receiver and network conditions is herein referenced as a universal streaming server.

FIG. 1 illustrates a streaming system 100 comprising a panoramic multimedia source 110 coupled to a universal streaming server 120 through a transmission medium 115. Transmission medium 115 may be a dedicated medium, such as a fiber-optic link or a wireless link, or may be a switched path through a shared telecommunication network. The panoramic multimedia server may communicate with a plurality of client devices 180, individually identified as 180(0) to 180(m), m>1, through a network 150. The panoramic multimedia source 110 comprises a full-coverage camera and may comprise a de-warping module and/or a compression module. A full-coverage camera, herein also called a 4π camera, produces a full-coverage video signal. A multimedia signal, herein referenced as a “source multimedia signal”, transmitted from the panoramic multimedia source 110 to universal streaming server 120 may contain a video signal in addition to signals of other forms such as an audio signal or a text signal.

FIG. 2 illustrates a streaming system 200 comprising a number ν, ν≥1, of panoramic multimedia sources 110, individually identified as 110(0) to 110(ν−1), and a number μ of universal streaming servers, μ≥1, individually identified as 120(0) to 120(μ−1) which may concurrently serve a number M, M>1, of client devices of a plurality of client devices 180. The universal streaming servers 120 may communicate with the panoramic multimedia sources 110 and the client devices through network 150. Alternatively, the universal streaming servers 120 may communicate with the panoramic multimedia sources 110 through one shared network (not illustrated) but communicate with the client devices 180 through another network (not illustrated).

A multimedia panoramic source 110 preferably employs a full-coverage panoramic camera, herein referenced as a 4π camera, providing view coverage of up to 4π steradians. An output signal of a 4π camera is herein referenced as a 4π video signal. A display of a 4π video signal of a captured scene on a flat screen may differ significantly from the actual scene due to inherent warping. To eliminate or significantly reduce the display distortion, an artificial offset distortion may be applied to the camera-produced signal so that the display closely resembles a captured scene. Numerous processes, called “de-warping”, for correcting the distorted video signal are known in the art.

The de-warping process may be implemented at source, i.e., directly applied to a camera's output signal, or implemented at the universal streaming server 120.

The video signal at a source 110 may be sent directly to a universal streaming server 120 over a high-capacity communication path or compressed at source to produce a compressed signal, occupying a (much) reduced spectral band, which is sent to a universal streaming server 120 over a lower-capacity communication path to be decompressed at the universal streaming server.

FIG. 3 illustrates four communication options between a multimedia panoramic source 110 and a server 120. The multimedia panoramic source includes a 4π camera which produces a raw signal 312 and may include a de-warping module 330 and/or a source compression module 340. The raw signal 312 need be de-warped before display or before further processing to condition the signal to specific recipients.

Communication devices coupled to the source are not illustrated in FIG. 3 . As illustrated in FIG. 3 , a first source comprises the 4π camera, a second source comprises the 4π camera and a de-warping module 330, a third source comprises the 4π camera and a source compression module 340, and a fourth source comprises the 4π camera, a de-warping module 330, and a source compression module 340.

According to one embodiment, the raw signal 312 may be sent to a server 120A equipped with a de-warping module 320 which produces a corrected signal 322 which is further processed to produce recipient-specific signals. The corrected signal is considered a “pure video signal” which corresponds to the respective scene captured at source.

According to another embodiment, the raw signal 312 may be processed at a de-warping module 330 coupled to the source 110 to produce a corrected signal (pure video signal) 322 which is sent to a server 120B for further processing to produce recipient-specific signals.

According to a further embodiment, the raw signal 312 may be processed at a source compression module 340 coupled to the source 110 to produce a compressed signal 342 which is sent to a server 120C. Server 120C is equipped with a server decompression module 350 which decompresses compressed signal 342 to produce a decompressed signal 352 to be processed at de-warping module 320 to produce a rectified signal 324. The rectified signal is a “pure video signal” as defined above. With a lossless compression process and an ideal decompression process, the decompressed signal 352 would be a replica of raw signal 312. With ideal de-warping, rectified signal 324 would be a faithful representation of the captured scenery.

According to a further embodiment, the raw signal 312 may be processed at a de-warping module 330 coupled to the source 110 to produce a corrected signal 322 which is processed at a source compression module 340 to produce a compact signal 343 to be sent to a server 120D. Server 120D is equipped with a server decompression module 350 which decompresses compact signal 343 to produce a rectified signal 324. With an ideal de-warping module 330, a lossless compression process, and an ideal decompression process, the rectified signal would be a faithful representation of the captured scenery, i.e., a “pure video signal”.

Thus, the present invention provides a method of video-signal streaming implemented at a server which comprises multiple physical processors and associated memory devices. The server is devised to acquire a panoramic multimedia signal comprising a video signal from:

-   -   (1) a signal source comprising a panoramic camera;     -   (2) a signal source comprising a panoramic camera and a         de-warping module;     -   (3) a signal source comprising a panoramic camera and a         compression module; or     -   (4) a signal source comprising a panoramic camera, a de-warping         module, and a compression module.

The method comprises a process of accessing a panoramic multimedia source to acquire a video signal. If the acquired video signal is uncompressed and has not been de-warped at source, the video signal is de-warped at the server to produce a “pure video signal” which may be displayed on a screen or further processed for distribution to client devices. If the acquired video signal is uncompressed and has been de-warped at source, the video signal constitutes a “pure video signal”. If the acquired video signal has been compressed but not de-warped at source, the video signal is decompressed then de-warped at the server to produce a “pure video signal. If the acquired video signal has been de-warped and compressed at source, the video signal is decompressed at the server to produce a “pure video signal.

FIG. 4 illustrates communication paths corresponding to the communication options of FIG. 3 .

According to the first communication option, a panoramic signal produced at a 4π camera 310, of panoramic multimedia source module 110A, is transmitted over a high-capacity path 480 to server 120A which comprises a de-warping module 320 and a signal-editing module 460 which performs both content filtering and signal adaptation to client devices under flow-rate constraints. Server 120A comprises at least one processor (not illustrated in FIG. 4 ) and memory devices storing processor executable instructions (software instructions) organized as the de-warping module 320 and the signal-editing module 460. The software instructions of de-warping module 320 are executed to cause the at least one processor to use the received signal and known characteristics of the camera to produce a de-warped corrected signal 322 which may be directly presented to a flat display device or further processed in signal-editing module 460. Signal-editing module 460 may perform content filtering processes to produce selective partial-coverage streams, each tailored to a respective recipient. Signal-editing module 460 may also produce full-coverage streams each tailored to a respective recipient.

According to the second communication option, source module 110B comprises a 4π camera 310, a de-warping module 330, and a processor (not illustrated) applying software instructions of de-warping module 330 to the output signal (raw signal 312) of the 4π camera. The resulting de-warped signal is sent over a high-capacity communication path 480 to server 120B which comprises a signal-editing module 460 as in the first implementation option above.

According to the third communication option, source module 110C comprises a 4π camera 310, a source compression module 340, and a processor (not illustrated) applying software instructions of source compression module 340 to the output signal (raw signal 312) of the 4π camera. The resulting compressed signal 342 is sent over a communication path 490, of a lower-capacity compared to communication path 480, to server 120C which comprises a server decompression module 350, a de-warping module 320, and signal-editing module 460. Server 120C comprises at least one processor (not illustrated) which implements software instructions of server decompression module 350 to produce decompressed signal 352. The at least one processor also implements software instructions of the de-warping module 320 to produce a rectified signal 324. Signal-editing module 460 performs content filtering of rectified signal 324 to produce selective partial-coverage streams, each tailored to a respective recipient. Signal-editing module 460 may also produce full-coverage streams each tailored to a respective recipient.

According to the fourth communication option, source module 110D comprises a 4π camera 310, a de-warping module 330, a source compression module 340, and a processor (not illustrated) applying software instructions of the de-warping module 330 to the output signal (raw signal 312) of the 4π camera to produce a corrected signal 322. The processor applies the software instructions of the source compression module 340 to produce a compact signal 343. The compact signal 343 is sent over a lower-capacity communication path 490 to server 120D which comprises a server decompression module 350 and the signal-editing module 460. Server 120D comprises at least one processor (not illustrated) which implements software instructions of server decompression module 350 to reconstruct the corrected signal 322. As in the previous communication options, signal-editing module 460 performs content filtering of rectified signal 324 to produce selective partial-coverage streams, each tailored to a respective recipient. Signal-editing module 460 may also produce full-coverage streams each tailored to a respective recipient.

With the first or second communication option, a corrected video signal 322 is presented to a signal-editing module 460. With the third or fourth communication options, a rectified video signal 324 is presented to a signal-editing module 460. Each of the corrected video signal 322 and the rectified video signal 324 is considered a pure video signal corresponding to a respective scene captured at source.

FIG. 5 illustrates components of an end-to-end path 500 corresponding to the first communication option of the communication options of FIG. 3 . Source 110A produces (baseband) raw signal 312 which is transmitted over high-capacity path 480 to server 120A. The high-capacity path 480 comprises a source transmitter 520 collocated with source 110A, transmission medium 115, and server receiver 540 collocated with server 120A. Receiver 540 demodulates modulated carrier signal 528 received through transmission medium 115 to acquire a replica 542 of the raw signal 312. Server 120A comprises a memory device storing software instructions constituting de-warping module 320 and a memory device storing software instructions constituting signal-editing module 460. Server 120A also comprises client-devices interfaces 560 which include server transmitters. Output signals 585 of server 120A are communicated through network 150 to respective client devices 180.

FIG. 6 illustrates components of an end-to-end path 600 corresponding to the second communication option of the communication options of FIG. 3 . Source 110B comprises 4π camera 310 and a memory device storing software instructions constituting de-warping module 330 which cause a processor (not illustrated) to produce corrected signal 322. Corrected signal 322 is transmitted over high-capacity path 480 to server 120B. The high-capacity path 480 comprises a source transmitter 520 collocated with source 110B, transmission medium 115, and server receiver 540 collocated with server 120B. Receiver 540 demodulates modulated carrier signal 628 received through transmission medium 115 to acquire a replica 642 of the corrected signal 322. Server 120B comprises a memory device storing software instructions constituting signal-editing module 460. Server 120B also comprises client-devices interfaces 560 which include server transmitters. Output signals 685 of server 120B are communicated through network 150 to respective client devices 180.

FIG. 7 illustrates components of an end-to-end path 700 corresponding to the third communication option of the communication options of FIG. 3 . Source 110C comprises 4π camera 310, which produces (baseband) raw signal 312, and a memory device storing software instructions constituting source compression module 340. Source compression module 340 compresses raw signal 312 into compressed signal 342 which is transmitted over path 490 to server 120C. Path 490 comprises a source transmitter 720 collocated with source 110C, transmission medium 115, and server receiver 740 collocated with server 120C. Receiver 740 demodulates modulated carrier signal 728 received through transmission medium 115 to acquire a replica 742 of compressed signal 342. Server 120C comprises a memory device storing software instructions constituting server decompression module 350, a memory device storing software instructions constituting de-warping module 320, and a memory device storing software instructions constituting signal-editing module 460. Server 120C also comprises client-devices interfaces 560 which include server transmitters. Output signals 785 of server 120C are communicated through network 150 to respective client devices 180.

FIG. 8 illustrates components of an end-to-end path 800 corresponding to the fourth communication option of the communication options of FIG. 3 . Source 110D comprises 4π camera 310, a memory device storing software instructions constituting de-warping module 330 which cause a processor (not illustrated) to produce corrected signal 322, and a memory device storing software instructions constituting source compression module 340 which cause a processor (not illustrated) to produce compact signal 343. Compact signal 343 is transmitted over path 490 to server 120D. Path 490 comprises a source transmitter 720 collocated with source 110D, transmission medium 115, and server receiver 740 collocated with server 120C. Receiver 740 demodulates modulated carrier signal 828 received through transmission medium 115 to acquire a replica 842 of compact signal 343. Server 120D comprises a memory device storing software instructions constituting server decompression module 350, and a memory device storing software instructions constituting signal-editing module 460. Server 120D also comprises client-devices interfaces 560 which include server transmitters. Output signals 885 of server 120D are communicated through network 150 to respective client devices 180.

FIG. 9 illustrates multimedia signals and control signals at input and output of a universal streaming server 120. The server 120 receives from a source 110 a multimedia signal including a video signal 900 which may be a raw signal 312, a corrected signal 322, a compressed signal 342, or a compact signal 343. A video signal received at a server from a source 110 is herein referenced as a “source video signal”.

The server 120 may receive multimedia signals from different panoramic multimedia sources 110 as illustrated in FIG. 2 . The server may, therefore receive a raw video signal 312 from a first source 110, a corrected video signal 322 from a second source 110, a compressed signal 342 from a third source, and/or a compact signal 343 from a fourth source. Preferably, then, the server may be equipped with a de-warping module 320 and a server decompression module 350 to be able to engage with sources 110 of different types and produce a pure video signal 420 which may be a corrected video signal 322 or a rectified video signal 324.

The server 120 receives upstream control signals 935 from client devices 180 and control signals 905 from sources 110. The server transmits downstream control signals 945 to client devices and may transmit control signals 925 to the source 110. Regardless of the source type, the kernel of the server, which is signal-editing module 460, processes the pure video signal 420 based on control signals 935 and 905.

The upstream control signals 935 may include clients' characterizing data and clients' requests. The downstream control signals 945 may include responses to clients' requests. The downstream control signals 945 may also include software modules to be installed at client devices 180 to enable each subtending client device to communicate preferred viewing regions to the server. Control signals 905 may include data relevant to source characteristics and operations already performed at source, such as de-warping and/or data compression. Control signals 925 may include information characterizing the server.

The signal-editing module 460 of the server 120 produces edited multimedia signals 940, each edited multimedia signal being individually conditioned to: viewing preference of a respective client; capability of a respective client's device; and condition of a network path from the server to the respective client's device. The server 120 transmits to client devices the edited multimedia signals 940.

FIG. 10 illustrates components 1000 of an exemplary server 120. The server comprises at least one processor (not illustrated) and multiple memory devices storing processor executable instructions organized into a number of modules including a server-network interface 1010, a source control-data module 1022, a source signal-processing module 1024, a client control-data module 1026, and a set of client-specific adaptation modules 1060. The server-network interface 1010 is coupled to at least one dual link 1008 to at least one network which carries all signals 1005 originating from, or destined to, signal sources and client devices. The server-network interface 1010 comprises a server receiver 540 (FIG. 5 and FIG. 6 ) or 740 (FIG. 7 and FIG. 8 ) which demodulates a modulated carrier (optical carrier or wireless microwave carrier) to detect the baseband source video signal 900 (raw signal 312, corrected signal 322, compressed signal 342, or compact signal 343) sent from a source 110 (110A, 110B, 110C, or 110D). A dual link of the at least one dual link 1008 carries: control data to and from at least one source 110 and a plurality of client devices; source multimedia signals; and edited multimedia signals directed to the plurality of client devices.

The source video-signal-processing module 1024 may be equipped with a de-warping module 320 and/or a server decompression module 350 to produce a pure video signal 420 which may be a corrected video signal 322 or a rectified video signal 324.

Server-network interface 1010 directs source video signals 900 to source video-signal-processing module 1024 and control signals 905 to source-control data processing module 1022. Source video-signal-processing module 1024 performs processes of:

-   -   (1) video-signal de-warping (module 320, FIG. 5 );     -   (2) video-signal decompression (module 350) and de-warping         (module 320, FIG. 7 ); or     -   (3) video-signal decompression (module 350, FIG. 8 ).

Modules 1022 and 1024 are communicatively coupled as indicated in FIG. 10 . Outputs of module 1022 may influence processes of module 1024. Module 1024 may generate control data 925 directed to a source 110 to be communicated through module 1022 and server-network interface 1010.

Module 1024 directs pure video signals 420 to a number m, m>1, of client-specific adaptation modules 1060, individually identified as 1060(0) to 1060(m−1). Client-specific adaptation modules 1060 preferably employ independent hardware processors. Each client-specific adaptation module 1060 comprises a memory device storing instructions which cause a respective processor to perform requisite transcoding functions.

The signals received from client devices comprises upstream control signal 935. The data directed to client devices comprises control signals 945 and edited multimedia signals 940. Upstream control signals 935 are extracted at server-network interface 1010 and directed to clients' control-data module 1026. The client-specific adaptation modules 1060 access upstream control data 935 through a client control bus 1061, where client-specific control signals are held in buffers 1062, or through other means known in the art. Downstream control data generated at the client-specific adaptation modules 1060 are distributed to respective client devices 180 through client control bus 1061, client control-data module 1026, server-network interface 1010, and the at least one dual link 1008. The edited client-specific multimedia signals 940 are combined (combiner 1090) and the aggregate stream 1095 is distributed to respective client devices 180 through server-network interface 1010, the at least one dual link 1008, and at least one network.

FIG. 11 details a client-specific adaptation module 1060. The module comprises at least one memory device storing processor-executable instructions which, when executed, cause at least one processor to perform processes of content filtering of a video signal to extract a signal corresponding to a selected view region and transcoding the content-filtered video signal to be compatible with the capability of a target client device 180. The video signal may be compressed under the constraint of a permissible flow rate which may be a representative value of a time-varying flow rate.

A client-specific adaptation module 1060 comprises a content-filtering module (content filter) 1120, a transcoding module 1140 for signal adaptation to client-device capability, and a server compression module 1160 for producing a video signal having a flow rate within a permissible flow rate.

In accordance with one embodiment, content filter 1120 processes the pure video signal 420 to extract signal portions which correspond to a specified view region yielding a content-filtered signal 1122. The mean flow rate of content-filtered signal 1122 would be lower than the mean flow rate of pure video signal 420. If content-filtered signal 1122 is compatible with the capability of a target client device and has a flow rate satisfying a respective permissible value, the signal may be transmitted to the target client device. Otherwise, transcoding module 1140 is applied to transcode content-filtered signal 1122 to be compatible with characteristics of the target client device such as an upper bound of a frame rate and a frame resolution upper bound. If the resulting transcoded content-filtered signal 1142 has a flow rate not exceeding the permissible value, signal 1142 may be transmitted to the target client device. Otherwise, server compression module 1160 may be applied to compress signal 1142 according to the permissible flow rate yielding signal 940 which is a compressed, transcoded, and content-filtered signal.

In accordance with another embodiment, transcoding module 1140 may be applied to transcode pure video signal 420 to yield a transcoded signal 1152 compatible with the capability of the target client device. Content filter 1120 processes signal 1152 to extract signal portions which correspond to a specified view region yielding a content-filtered transcoded signal 1132. The mean flow rate of content-filtered transcoded signal 1132 would be lower than the mean flow rate of pure video signal 420. If signal 1132 has a flow rate satisfying a permissible value, the signal may be transmitted to the target client device. Otherwise, server compression module 1160 may be applied to compress signal 1132 according to the permissible flow rate yielding signal 940 which is now a compressed, transcoded, and content-filtered signal.

An uncompressed or decompressed video signal which is de-warped at the source or at the server is a pure video signal. To provide service to a specific client device, the pure video signal is transcoded to produce a transcoded signal compatible with the client device. The pure video signal corresponds to an attainable coverage of a solid angle of up to 4π Steradians and is likely to have a large flow rate (bit rate), of multi-Gb/s for example, which may exceed the available capacity of a path from the server to the client device. The transcoded signal may also have a flow rate that exceeds the capacity of the path. Thus, the transcoded signal may be compressed to yield a flow rate not exceeding the capacity of the path.

The compressed transcoded signal is transmitted to the client device to be decompressed and displayed at the client device. A viewer at the client device may then identify a preferred view region and send descriptors of the preferred view region to the server. The signal may then be content-filtered to retain only portions of the signal that correspond to the preferred view region. The content-filtered signal may be compressed then transmitted to the client device.

When the server accesses the panoramic multimedia source 110, the panoramic multimedia source provides a multimedia signal comprising the video signal as well control data including indications of any signal processing applied to the video signal, such as de-warping and compression. The acquired video signal is a panoramic video signal which may be produced by a single camera or produced by combining video signals from multiple cameras.

To enable a user of the client device to communicate identifiers of a preferred view region, the server sends to the client device a software module devised for this purpose. The server may be partially or entirely installed within a shared cloud-computing network where the physical processors and associated memory devices are allocated as the need arises.

FIG. 12 illustrates temporal variation of the flow rate (bit rate) of a compressed video signal. As well known in the art, a number of descriptors may be used to characterize a variable-flow-rate signal (also called a variable-bit-rate) such as a mean value 1220 and a peak value 1230 of the flow rate, and a parameter representing signal-burst duration. The descriptors and the capacity of a shared network path designated to transport the variable-bit-rate signal may be used to determine an effective flow rate (effective bit rate) 1225 which need be allocated in a communication path to transport the signal. Server compression module 1160 would be devised to ensure that the effective flow rate (effective bit rate) does not exceed a permissible flow rate of a (purchased) network connection.

FIG. 13 illustrates modules 1300 for generating time-limited video signals of reduced flow rates yet suitable for exhibiting panoramic full spatial coverage to enable a client receiving a time-limited video signal to select a preferred partial-coverage view.

Frame-sampling module 1320 comprises processor executable instructions which cause a processor to sample a pure video signal 420, or a transcoded video signal derived from the pure video signal, during distant frame intervals to produce a frame-sampled video signal 1322 corresponding to full spatial-coverage sampled images. Frame-sampled video signal 1322 is not compressed and has a constant flow rate not exceeding a permissible flow rate. The frame-sampled video signal 1322 may be displayed at a client device.

Pure video signal 420 may be a corrected signal 322 or a rectified signal 324 (FIG. 3 ). The inter-frame sampling period is selected so that the (constant) flow rate of the stream of sampled portions of a pure video signal 420 does not exceed a permissible flow rate. For example, if the data flow rate of a pure video signal 420 is 1 Gb/s and the permissible flow rate is 5 Mb/s, then frame-sampling module 1320 would select one frame out of each set of 200 successive frames. A specific client device 180 receiving the sampled frames would then display each frame repeatedly during a period of 200 frame intervals (5 seconds at a frame rate of 40 frames per second). The server 120 starts to send a respective edited multimedia signal 940 (FIG. 9 ) and terminates transmitting frame samples after the server receives an indication of a preferred view region from the specific client device.

The server 120 may send view-selection software instructions to each client device to facilitate client's selection of a preferred view region. The software instructions may be sent along the same path carrying downstream control data 945 (FIG. 9 ).

Thus, server 120 may employ a frame-sampling module comprising processor executable instructions which cause a processor to sample a video signal during distant frame intervals to produce a frame-sampled video signal. The server further comprises a memory device storing software modules for distribution to the plurality of client devices to enable users of the client devices to communicate identifications of preferred viewing regions to the server.

Spatial-temporal server compression module 1340 comprises processor executable instructions which cause a processor to compress pure video signal 420, or a transcoded video signal derived from the pure video signal, to produce a compressed signal 1342 corresponding to full spatial-coverage images. Compressed signal 1342 would have a fluctuating flow rate as illustrated in FIG. 12 and server compression module 1340 ensures that the effective flow rate (effective bit rate) does not exceed a permissible flow rate.

A spatial-temporal compression module 1360, similar to spatial-temporal server compression module 1340, causes a processor to compress preselected content-filtered signals (partial coverage signals) 1362 derived from a pure video signal 420. A succession of compressed content filtered signals 1364, occupying successive time windows, is sent to a target client device. Each of compressed signals 1364 would have a fluctuating flow rate as illustrated in FIG. 12 and compression module 1360 ensures that the effective flow rate (effective bit rate) of each compressed signal 1364 does not exceed a permissible flow rate.

FIG. 14 illustrates a process of providing a content-filtered video signal to a client device. At an instant of time t₁, a user of a specific client device 180 sends a message 1402 to a server 120 requesting viewing of a specific event. The message is received at the server 120 at time t₂. Several view-selection methods may be devised to enable a user of the specific client device to communicate identifiers of a preferred view region to the server.

In one view-selection method, the server sends a frame-sampled signal 1322, which corresponds to selected full spatial-coverage panoramic images, at time t₃. At time t₄, the client device 180 starts to receive frame-sampled signal 1322 which is submitted to a display device after accumulating content of one frame. At time t₅, the user of the specific client device sends a message 1404 providing parameters defining a selected view region. Message 1404 is received at the server at time t₆. The server 120 formulates a respective content filtered video signal corresponding to the selected view region. The respective content filtered video signal may be compressed to produce a compressed content-filtered signal (partial-spatial-coverage signal) 1440. The server terminates transmission of the frame-sampled signal 1322 at time t₇ and starts to send compressed content-filtered signal 1440 to the client device 180 at time t₉. Signal 1440 is decompressed and displayed at the client device. The client device receives the last frame of frame-sampled signal 1322 before time t₈ and starts to receive compressed signal 1440 at time t₁₀. Transmission of compressed signal 1440 ends at time t₁₁ and receiving the signal at the client device ends at time t₁₂.

In another view-selection method, the server generates a full-coverage video signal 1342 that is client-device compatible and compressed to a permissible flow rate as illustrated in FIG. 13 . The server sends the signal 1342 at time t₃ and the client device 180 starts to receive the compressed signal at time t₄. The compressed signal 1342 is decompressed at the client device and submitted to a display device. The sequence of events after time t₄ would be similar to the sequence of events corresponding to the case of frame-sampled video signal 1322.

In a further view-selection method, the server derives from pure video signal 420 several content-filtered video signals 1362 corresponding to preselected view regions as illustrated in FIG. 13 . Each of the derived content-filtered video signals would be compatible with the capability of the client device and compressed to a permissible flow rate. A succession of compressed signals 1364 may be sent to the client device and a user of the client device may send a message to the server indicating a preferred one of the preselected view regions.

Thus, the present invention provides a method of signal streaming comprising editing content of the video signal to produce a set of content-filtered signals corresponding to a predefined set of view regions. Each content-filtered signal is transcoded to produce a set of transcoded signals compatible with a particular client device. Each of the transcoded signals is compressed to produce a set of compressed signals. The compressed signals are successively transmitted to the client device. Upon receiving from the particular client device an identifier of a specific compressed signal corresponding to a preferred view region, only the specific compressed signal is subsequently transmitted to the client device.

FIG. 15 illustrates temporal bit-rate variation (flow rate variation) of video signals transmitted from a server 120 to a client device 180. The bit rate of frame-sampled signal 1322 is constant and set at a value not exceeding a predefined permissible bit rate. The bit rate of compressed content-filtered signal 1440 is time variable. As well known in the art, a variable bit rate may be characterized by parameters such as a mean bit rate, a peak bit rate, and a mean data-burst length. The parameters, together with the capacity of a respective network path, may be used to determine an “effective bit rate” 1525 which is larger than the mean bit rate 1520. The formulation of the frame-sampled signal 1322 ensures that the resulting constant bit rate does not exceed the predefined permissible bit rate (which may be based on a service-level agreement or network constraints). The compression process at the server 120 is devised to ensure that the effective bit rate of the compressed signal 1440 does not exceed the permissible bit rate.

To provide service to a set client devices of a specific client device, the pure video signal may be transcoded to produce a transcoded signal compatible with the client-device type. The transcoded signal may have a flow rate that exceeds the capacity of some of the paths from the server to the client devices. To provide the client devices with a full-coverage (attainable-coverage) view, a signal sample of a reduced flow rate is generated and multicast to client devices. A signal sample may be a frame-sampled transcoded signal or a compressed transcoded signal. Upon receiving from a particular client device an identifier of a respective preferred view region, the transcoded signal is content-filtered to produce a client-specific signal corresponding to the respective preferred view region. The client-specific signal is compressed and transmitted to the particular client device.

Signal-Editing Module

FIG. 16 illustrates basic components 1600 of signal-editing module 460 (FIG. 4 to FIG. 8 ) of a server 120. In a first stage 1610, the pure video signal 420 is processed to produce a number K, K≥1, of content-filtered signals 1612. In a second stage 1620, each content-filtered signal 1612 is adapted to a respective client device or a group of client devices 180. Each content-filtered signal is directed to a respective signal-processing unit 1630 to produce a respective conditioned signal 1650 satisfying a number of conditions including upper bounds of frame-rate, resolution, and flow rate (bit rate). A conditioned signal 1650 may be suitable to multicast to a number of client devices. The content-filtered signals 1612 are individually identified as 1612(0) to 1612(K−1). The signal-processing units 1630 are individually identified as 1630(0) to 1630(K−1). The conditioned signals 1650 are individually identified as 1650(0) to 1650(K−1).

FIG. 17 illustrates a content-filtering stage 1610 comprising K content filters 1120, individually identified as 1120(0) to 1120(K−1), for concurrent generation of different partial-content signals from a full-content signal. A full-content signal 900 received through server-network interface 1710 may be decompressed and/or de-warped (modules 1725) to produce a pure video signal 420 which is muted to inputs of all content filters 1120. Parameters identifying requested contents are distributed to control inputs 1720 of the content filters 1120.

Each content filter 1120 is devised to cause a physical processor (not illustrated) to extract portions of pure video signal 420 which corresponds to a specified view region. The pure video signal 420 is submitted to each content filter 1120 which is activated to produce a corresponding content-filtered signal 1612. A particular content-filtered signal 1612 may be multicast to a number of clients that have indicated preference of the view region corresponding to the particular content-filtered signal. However, the client devices may have different characteristics, the capacities of network paths to the client devices may differ, and the permissible flow rates to the client devices may differ due differing network-path capacities and time-varying traffic loads at the client devices. Thus, content-filtered signals 1612 are processed in the second stage 1620 for adaptation to client devices and network-paths.

FIG. 18 illustrates a signal-processing unit 1630, of the second stage 1620 of the signal-editing module 460, comprising a transcoding module 1840 for signal adaptation to client-device types and modules 1860 for signal flow-rate adaptation to conform to permissible flow-rates. A transcoding module 1840 may adapt a video signal to have a frame rate and resolution within the capability of a respective client device. With N types of active client devices, N≥1, a transcoding module 1840 produces N signals 1842, individually identified as 1842(0) to 1842(N−1), each adapted to a respective device type. A module 1860 may further reduce the flow rate of a signal if the flow rate exceeds a permissible value. Each module 1860(j), 0≤j<N, comprises a buffer 1861 for holding a data block of a respective signal 1842 and a memory device 1862 storing processor-executable instruction for flow-rate adaptation.

FIG. 19 illustrates a complete structure 1900 of the signal-editing module 460. The content filtering stage 1610 comprises K content filters 1120 as illustrated in FIG. 17 . Each content-filtered signal 1612 is submitted to a transcoding module 1840 to adapt the signal to a respective client-device type. A transcoding module 1840 comprises a buffer 1922 for holding a data block of a content-filtered signal 1612 and a memory device 1923 storing processor executable instructions which cause a processor to modify the frame rate and/or resolution to be compatible with the capability of a client-receiver. Each output signals 1842 of a transcoding module 1840 may be further processed at a flow-rate adaptation module 1860.

As illustrated in FIG. 17 , K content filters 1120, individually identified as 1120(0) to 1120(K−1), K>1, may be activated simultaneously to extract different content-filtered signals 1612(0) to 1612(K−1) each further processed at a respective signal-processing unit 1630 to produce a signal 1650 suitable for display at a respective client device or a set of client devices. As illustrated in FIG. 18 , a content-filtered signal 1612 is transcoded to be compatible with a target client device 180 and further adapted to a flow rate not exceeding a permissible upper bound.

FIG. 20 illustrates processes 2000 of video signal editing for a target client device 180. Control signals 935 may provide traffic-performance measurements 2014, a nominal frame rate and frame resolution 2016, and identifiers 2012 of a preferred view region. A pure video signal 420 is directed to a content filter 1120(j) to extract content of pure video signal 420 that corresponds to a view region j identified by a user of the target client device. Flow-rate computation module 2040 is activated to determine a permissible flow rate D as well as a frame rate and frame resolution, compatible with the target client device 180, to be used in transcoding module 1840(j). Transcoding module 1840(j) is activated to adapt the extracted content-filtered signal 1612(j) to the frame rate and frame resolution determined by flow-rate computation module 2040. Server compression module 2030 produces an edited video signal 940 (FIG. 9 ) which corresponds to an identified view region and is adapted to the capability of the target client device 180 and the capability of the network path from the server 120 to the target client device 180. Transmitter 2050 sends a signal 2052 to the target client device. Signal 2052 comprises video signal 940 together with accompanying multimedia signals (such as audio signals and/or text) and control signals. Signal 2052 is routed to the target client device along a network path 2060.

FIG. 21 details flow-rate computation module 2040. Starting with a nominal frame rate and nominal frame resolution of the target client device 180, which may be stored at the server or included in control signals 935 received from the target client, process 2110 determines the requisite flow rate R at the display device of the target client device 180 as a direct multiplication of the frame rate, the number of pixels per frame, and the number of bits per pixel. Independently, process 2120 determines a permissible flow rate Φ (reference 2122) between the server and the target client device based on measurements of traffic performance along the network path 2060 and the occupancy of a receiving buffer at the client device. The traffic-performance measurements include a data-loss indicator (if any) and delay jitter. The traffic-performance measurements are determined using techniques well known in the art. Determining the permissible flow rate based on measured traffic performance may be based on empirical formulae or based on a parameterized analytical model.

Process 2140 determines whether the compression ratio (determined in process 2130) of the requisite flow rate R at the display device of the target client server to the permissible flow rate Φ along the network path 2060 is suitable for server compression module 2030. If the flow rate R is to be reduced to satisfy a compression-ratio limit, process 2150 may determine a revised frame rate and/or a revised resolution 2152 to be communicated to transcoding module 1840 (FIG. 20 ). The permissible flow rate Φ may be communicated to server compression module 2030.

FIG. 22 illustrates components of a client device 180. A memory device 2210 stores client-device characterizing data, such as upper bounds of a frame rate and frame resolution of a display device. A memory device 2220 stores software instructions for interacting with specific servers 120. The instructions may include software modules to enable a user of a client device to communicate identifications of preferred viewing regions to the server. The software instructions may be installed by a user of a client device or sent from a server 120 together with the downstream control signals 945 (FIG. 9 ). A client transmitter 2230 transmits all control data from the client device to respective servers 120. A client receiver 2240 receives all signals from server(s) 120 including edited video signal 940 (which may be compressed), other multimedia data (audio signals and text), and control signals 945. An interface 2242 directs control signals 945 to processor 2250 and edited video signal 940, together with accompanying audio signals and text, to a memory device 2260 which buffers data blocks of incoming multimedia data comprising the video signal 940, audio data, and text. If the incoming multimedia data is not compressed, the data may be presented to the display device 2290. Otherwise, client decompression module 2270 decompresses the compressed data block buffered in memory device 2260 to produce display data to be held in memory device 2280 coupled to the display device 2290. Notably, a data block corresponding to one frame of a full-coverage frame-sampled signal 1322 (FIG. 13 , FIG. 14 ) may be displayed numerous times before de-queueing from memory device 2280.

FIG. 23 illustrates communication paths between a universal streaming server 120 and two panoramic multimedia sources 110-0 and 110-1 through network 150. A multimedia source 110 comprises a panoramic camera 310 (e.g., a 4π camera), and may include a de-warping module 330 and/or a source compression module 340 as illustrated in FIGS. 3 to 8 . Although only two panoramic multimedia sources 110 are illustrated, it should be understood that the universal streaming server 120 may simultaneously connect to more multimedia sources 110 as illustrated in FIG. 2 . In a preferred implementation, the universal streaming server is cloud-embedded so that the network connectivity and processing capacity of the universal streaming server may be selected to suit varying activity levels. A source multimedia signal from a panoramic multimedia source 110 is transmitted to the universal streaming server 120 through a network path 480/490 (FIG. 4 ) of an appropriate transmission capacity. The source multimedia signal includes a source video signal 900.

With an ideal network path 480/490, the received multimedia signal at the universal streaming server 120 would be a delayed replica of the transmitted video signal. The network path 480/490, however, may traverse a data router at source, a data router at destination, and possibly one or more intermediate data routers. Thus, the received multimedia signal may be subject to noise, delay jitter, and possibly partial signal loss. With signal filtering at the server 120 and flow-rate control, the content of the received multimedia signal would be a close replica of the content of the transmitted multimedia signal.

The source video signal 900 may be a “raw” video signal 312 produced by a panoramic camera, a corrected video signal 322, a compressed video signal 342, or a compact video signal 343 as illustrated in FIG. 3 . A corrected video signal 322 is produced from the raw video signal using de-warping module 330. A compressed video signal 342 is produced from the raw signal 312, using source compression module 340 (FIG. 3 ), according to one of standardized compression methods or a proprietary compression method. A compact video signal 343 is produced from a corrected video signal 322 using a source compression module 340. The raw video signal may be produced by a single panoramic camera or multiple cameras.

The universal streaming server 120 may send control signals 925 (FIG. 9 ) to the panoramic multimedia source 110 through a network path 2314, which would be of a (much) lower transmission capacity in comparison with the payload path 480/490.

FIG. 24 illustrates a network 150 supporting a universal streaming server 120, a signal source 110 providing panoramic multimedia signals, and a plurality of client devices 180. Although only one signal source is illustrated, it should be understood that the universal streaming server 120 may simultaneously connect to multiple signal sources as illustrated in FIG. 2 . Communication paths are established between the universal streaming server 120 and a plurality of heterogeneous client devices 180. The universal streaming server 120 sends edited multimedia signals 940 (FIG. 9 ) to the client devices through network paths 2412. The universal streaming server 120 receives control data 935 from individual client devices 180 through control paths (not illustrated) within network 150. The control data 935 may include requests for service and selection of view regions.

A source multimedia signal from the source 110 is transmitted to the server 120 through a payload network path 480/490 of sufficiently high capacity to support high-flow rate. The multimedia signal includes a source video signal 900 (FIG. 3, 312, 322, 342 , or 343). Control signals from the server 120 to the signal source 110 are transmitted over a control path which would be of a much lower capacity in comparison with the payload network path 480/490. A video signal component 900 of the source multimedia signal may be an original uncompressed video signal produced by a panoramic camera or a compressed video signal produced from the original video signal according to one of standardized compression methods or a proprietary compression method. The original video signal may be produced by a single panoramic camera or multiple cameras.

With an ideal network path, the received video signal at the server 120 would be a delayed replica of the transmitted video signal. The network path, however, may traverse a data router at source, a data router at destination, and possibly one or more intermediate data routers. Thus, the received multimedia signal may be subject to noise, delay jitter, and possibly partial signal loss. The universal streaming server 120 receives commands from individual client devices 180. The commands may include requests for service, selection of viewing patterns, etc.

The video signals, individually or collectively referenced as 940, from the universal streaming server to client devices 180 are individually adapted to capabilities of respective client devices 180, available capacities (“bandwidths”) of network paths, and clients' preferences. Control data from individual client devices to the universal streaming server are collectively referenced as 935 (FIG. 9 ). The universal streaming server 120 may be implemented using hardware processing units and memory devices allocated within a shared cloud computing network. Alternatively, selected processes may be implemented in a computing facility outside the cloud.

FIG. 25 illustrates a path 480/490 carrying multimedia signals from a source 110 to a server 120 and a dual control path 2512 carrying control signals 905 from the source 110 to the server 120 and control signals 925 from the server 120 to the source 110. Downstream network path 2525 carries multimedia signals from the server 120 to a client 180. Dual control path 2526 carries downstream control signals to a client device 180 and upstream control signals 935 from the client device 180 to the server 120. An automaton 2545 associated with a client device 180 may send commands to the universal streaming server. The automaton would normally be a human observer. However, in some applications, a monitor with artificial-intelligence capability may be envisaged.

Client-specific multimedia signals 940 adapted from a panoramic multimedia signal 900 generated at the multimedia source 110 may be multicast to the plurality of heterogeneous client devices 180. The multimedia signals 940 are individually adapted to capabilities of respective client devices, available capacities (“bandwidths”) of network paths, and clients' preferences.

FIG. 26 illustrates a modular structure of the universal streaming server 120 comprising at least one hardware processor 2610. A server-source interface 2651 controls communication with the multimedia source 110. A source-characterization module 2652 characterizes the multimedia source 110 and communicates source-characterization data to a set 2620 of modules devised to process the received panoramic video signal 900. The source-characterization data may be determined from characterization data communicated by a panoramic multimedia source or from stored records. The set 2620 of modules includes a signal filtering module 2621, for offsetting signal degradation due to transmission noise and delay jitter, and may include a server decompression module 350 and a de-warping module 320 (FIG. 3 ). The signal-filtering module 2621 offsets signal degradation caused by noise and delay jitter. If the “raw” video signal 312 (FIG. 3 ) has been de-warped at source to produce a “corrected signal” 322 that is further compressed at source, the server decompression module 350 applies appropriate decompression processes to produce a replica of the corrected signal 322. Otherwise, if the raw video signal 312 has been compressed at source without de-warping, the server decompression module 350 applies appropriate decompression processes to produce a replica of the raw signal 312 which is then de-warped using de-warping module 320.

The client-device related modules 2640 include a client-device characterization module 2642 and a module 2643 for signal adaptation to client-device characteristics. The client-device characterization module 2642 may rely on a client-profile database 2641 that stores characteristics of each client-device type of a set of client-device types or extract client-device characteristics from characterization data received via server-client interface 2661. A client's device characteristics may relate to processing capacity, upper bounds of frame rate, frame resolution, and flow rate, etc.

Client-specific modules 2660 include server-client interface 2661, a module 2662 for signal adaptation to a client's environment, and a module 2663 for signal adaptation to a client's viewing preference.

FIG. 27 illustrates a universal streaming server 120 including a learning module 2725 for tracking clients' selections of viewing options. The learning module may be configured to retain viewing-preference data and correlate viewing preference to characteristics of client devices and optionally clients' environment.

Thus, the server comprises a network interface module devised to establish, through at least one network, communication paths to and from at least one panoramic video source; and a plurality of client devices. Various designs may be considered to construct the universal streaming server 120 based on the following modules:

-   -   a decompression module devised to decompress a video signal that         has been compressed at source;     -   a de-warping module devised to de-warp a video signal which has         not been de-warped at source;     -   a transcoding module devised to adapt a video signal to         characteristics of any client device of the plurality of client         devices;     -   a content filter devised to edit content of a video signal to         correspond to an identified view region; and     -   a control module devised to communicate with at least one         panoramic video source to acquire source video signals, present         video signals to the transcoding module and the content filter         to generate client-specific video signals, and send the         client-specific video signals to respective client devices.

The server may further use a learning module devised to retain viewing-preference data and correlate viewing preference to characteristics of client devices.

FIG. 28 illustrates processes performed at universal streaming server 120 where a panoramic video signal is adapted to client-device types then content filtered. In process 2820, a received source video signal 900 is decompressed if the source video signal 900 has been compressed at source. The received source video signal 900 is de-warped if the source video signal has not been de-warped at source. Process 2820 produces a pure video signal 420 (FIG. 4 to FIG. 8 ), which may be a corrected video signal 322 or a rectified video signal 324 (FIG. 3 ) as described above. Multiple processes 2830 may be executed in parallel to transcode pure video signal 420 to video signals adapted to different types of client devices.

Each of processes 2830 is specific to client-device type. A process 2830 transcodes the pure video signal 420 resulting from process 2820 to produce a modified signal suitable for a respective client-device type. Several clients may be using devices of a same type. However, the clients may have different viewing preferences. A video signal produced by a process 2830 is adapted in content filter 1120 to a view-region selection of a respective (human) client. However, if two or more clients using devices of a same type also have similar viewing preferences, a single content-filtering process may be executed and the resulting adapted signal is transmitted to the two or more clients.

FIG. 29 illustrates processes performed at universal streaming server 120 where a panoramic video signal is content filtered then adapted to client-device types. As in process 2820 of FIG. 28 , a received source video signal 900 is decompressed if the source video signal 900 has been compressed at source. The received source video signal 900 is de-warped if the source video signal 900 has not been de-warped at source. Process 2820 produces a pure video signal 420, which may be a corrected video signal 322 or a rectified video signal 324 (FIG. 3 ) as described above. A memory device stores a set 2925 of predefined descriptors of partial-coverage view regions.

Multiple processes of content filtering of pure video signal 420 may be executed in parallel to produce content-filtered video signals corresponding to the predefined descriptors of partial-coverage view regions. Multiple processes 2940 may be executed in parallel to adapt a content-filtered video signal to different types of client devices. If two or more clients select a same view region and use client devices of a same type, a single process 2940 is executed and the resulting adapted video signal is transmitted to the two or more clients.

FIG. 30 illustrates a method 3000 of acquisition of a panoramic multimedia signal and adapting the acquired multimedia signal to individual clients. The universal streaming server 120 acquires a panoramic multimedia signal and, preferably, respective metadata from a selected panoramic multimedia source 110 (process 3010). The acquired panoramic multimedia signal includes a source video signal which may be a raw video signal 312, corrected video signal 322, compressed video signal 342, or a compact video signal 343 as illustrated in FIG. 3 . The source video signal is filtered to offset degradation caused by noise and delay jitter (process 3012) and decompressed if the signal has been compressed at source (process 3014). The so-far-processed signal is de-warped if not originally de-warped at source (process 3018). Processes 3010 to 3018 yield a pure video signal 420.

When a service request is received from a client (process 3020), the pure video signal 420 is adapted to the characteristics of the client's device (process 3022). The adapted signal is compressed (process 3026) and transmitted to the client device (process 3028). Process 3026 takes into consideration flow-rate constraints which may be dictated by condition of the network path from the server to the client device

The client may prefer a specific view region and communicate with the universal streaming server 120 to define the preferred view region. Upon receiving a control signal 3030 from the client specifying a preferred view region (process 3032), the adapted signal produced in process 3022 is content filtered (process 3034), compressed (process 3026), and transmitted to the client device (process 3028). The pure view signal 420 may be content-filtered several times during a streaming session.

FIG. 31 illustrates a method 3100, similar to the method of FIG. 30 , of acquisition of a panoramic multimedia signal and adapting the acquired multimedia signal to individual clients. The only difference is the order of executing processes 3010, 3020, and 3022.

FIG. 32 illustrates an exemplary streaming-control table 3200, maintained at the universal streaming server 120, corresponding to a specific panoramic multimedia source 110. An edited multimedia signal 940 (FIG. 9 , FIG. 24 ) delivered to a specific client device 180 depends on the characteristics of the client device and on the viewing preference of a viewer using the client device. With a large number of client devices 180 connecting concurrently to a universal streaming server 120 (watching an activity in real time), it is plausible that:

-   -   (i) numerous clients use client devices 180 of the same         characteristics but the clients have differing viewing         preferences;     -   (ii) numerous clients have similar viewing preferences but use         client devices of differing characteristics; and/or     -   (iii) two or more clients use client devices of the same         characteristics and have the same viewing preference.

Thus, to reduce the processing effort of the universal streaming server 120:

-   -   module 2643 of signal adaptation to client device may be         exercised only once for all client devices of the same         characteristics then module 2663 of signal adaptation to client         viewing preference is exercised only once for all clients having         similar client devices and similar viewing preferences; or     -   module 2663 of signal adaptation to client viewing preference         may be exercised only once for all clients having similar         viewing preferences then module 2643 of signal adaptation to         client device is exercised only once for all clients having         similar viewing preferences and similar client devices.

As described earlier, module 2643 is devised for signal adaptation to client-device characteristics and module 2663 is devised for signal adaptation to a client's viewing preference.

The clients' requests for service may arrive in a random order and a simple way to track prior signal adaptation processes is to use a streaming-control table 3200 (FIG. 32 ). Streaming-control table 3200 is null initialized. In the example of FIG. 32 , there are eight types of client devices 180, denoted D0, D1, . . . , D7, and there are six view options denoted V0, V1, . . . , V5, quantified, for example, according to viewing solid angles. A first client accessed the universal streaming server 120 using a client device of type D1 and requested viewing option V3. A stream denoted stream-0 is then created and indicated in streaming-control table 3200. Another stream, denoted stream 1, is created for another client using a client device 180 of type D5 and specifying viewing option V2, and so on. Only six streams are identified in streaming-control table 3200, but it is understood that with a large number of simultaneously connected client devices 180 there may be numerous streams. When a new request from a client is received, streaming-control table 3200 is accessed to determine whether a new stream need be created or an existing stream be directed to the client. All of the streams corresponding to a device type are herein said to form a “stream category”.

FIG. 33 illustrates a streaming control process 3300 of initial adaptation of a video-signal for a specific client device 180. A request for service is received at server-client interface module 2661 from a client device 180 (process 3310) and the type of client device 180 is identified (process 3312). Process 3314 determines whether the device type has been considered.

If the client device type has not been considered (process 3314), a new stream category is created (process 3320) and the corresponding pure video signal 420 is adapted to the device type (process 3322). The new stream category is recorded (process 3324), a new stream is created (process 3326) and transmitted to the specific client device (process 3330).

If the device type has already been considered (process 3314), a stream category is identified (process 3316). At this point, the client may not have indicated a viewing preference and a default viewing option may be assigned. If a stream corresponding to an identified view region has already been created (process 3326), the stream is transmitted to the specific client device (process 3330). Otherwise, a new stream is created (process 3326) and transmitted to the specific client device (process 3330).

FIG. 34 illustrates an exemplary table 3400 produced by the learning module 2725 indicating a count of viewing options for each type of client devices 180. Eight client-device types denoted D0, D1, . . . , D7 and six viewing options denoted V0, V1, . . . , V5 are considered. The table may accumulate a count of selections of each stream defined by a device type and a viewing option over a predefined time window which may be a moving time window.

In the exemplary table of FIG. 34 , the most popular viewing option for clients using the client-device denoted D1 is viewing option V3 (selected 64 times over the time window). Thus, a new request for service received at the universal streaming server 120 from a client device of type D1 may be initially assigned viewing option V3.

Thus, the invention provides a method of signal streaming implemented at a server which may be implemented using hardware processing units and memory devices allocated within a shared cloud-computing network. The method comprises processes of multicasting a signal to a plurality of clients, receiving from a specific client a request to modify content of the signal, producing a modified signal, and transmitting the modified signal to the specific client. The signal may be derived from a panoramic multimedia signal containing a panoramic video signal produced by a single camera or produced by combining video signals from multiple cameras. The modified signal may be a partial-coverage multimedia signal.

In order to produce the modified signal, the method comprises processes of de-warping a video-signal component of the signal to produce a de-warped video signal and adapting the de-warped video signal to the client device to produce a device-specific video signal. The device-specific signal may be adapted to a viewing-preference of a client. The viewing preference may be stated in a request received from a client or be based on a default value specific to a client-device type.

The method comprises a process of acquiring characteristics of client devices which communicate with the server to request streaming service. A record of the characteristics of the client device and viewing preference may be added to a viewing-preference database maintained at the server.

The invention further provides a method of signal streaming performed at a server which may be fully or partially implemented using resources of a cloud computing network. The server may acquire a panoramic multimedia signal then decompress and de-warp a video-signal component of the panoramic multimedia signal to produce a pure video signal. For a given client device of a plurality of client devices:

-   -   (i) the pure video signal is content filtered to produce a         respective content-filtered signal which corresponds to a         selected view region; and     -   (ii) the content-filtered signal bound to a client device is         adapted to characteristics of the client device as well as to         characteristics of a network path from the server to a target         client device.

Each client device comprises a processor, a memory device, and a display screen. A client device may send an indication of viewing preference to the server. The server produces a respective content-filtered signal, corresponding to the viewing preference, to be sent to the client device.

The server may further perform processes of:

-   -   (a) retaining data relating viewing preference to         characteristics of clients' devices; and     -   (b) using the retained data for determining a default viewing         preference for each client device of the plurality of client         devices.

The server may acquire a panoramic video signal that is already de-warped and compressed at source then decompress the panoramic video signal to produce a pure video signal. A set of modified signals is then produced where each modified signal corresponds to a respective partial-coverage pattern of a predefined set of partial-coverage patterns. Upon receiving connection requests from a plurality of client devices, where each connection request specifies a preferred partial-coverage pattern, the server determines for each client device a respective modified signal according a respective preferred partial-coverage pattern. The respective modified signal bound to a particular client device may further be adapted to suit characteristics of the particular client device and characteristics of a network path to the particular client device.

FIG. 35 illustrates processes 3500 of downstream signal flow-rate control based on signal-content changes and performance metrics. A flow controller of the server implements one of two flow-control options. In a first option (option 0), an encoder of a content-filtered video signal enforces (Process 3542) a current permissible flow rate. In a second option (option 1), the flow controller communicates (process 3544) with a controller of a network which provides a path from the server to a client device to reserve a higher path capacity or to release excess path capacity.

A network interface (1010, FIG. 10 ) of server 120 receives upstream control data from a client device 120 which may contain definition of a preferred video-signal content as well as performance measurements. As well known in the art, the traffic performance of a communication path connecting a first device to a second device may be evaluated by exchanging control data between the first device and the second device. The first device may send indications of transmitting time and data-packet indices, the second device may detect delay jitter and/or data-packet loss and communicate relevant information to the first device. Additionally, the second device may track processing delay or packet-buffer occupancy at a decoder of the second device; such information would be indicative of a current processing load at the second device which may require reducing the flow rate from the first device to the second device.

The network interface receives the upstream control data and extracts performance-measurement data (process 3510). The flow controller determines performance metrics using methods well known in the art. The performance measurement may include data loss, delay jitter, and occupancy of a buffer at a client device holding data detected from carrier signals received at the client device from the server 120. The performance measurements correspond to a current permissible flow rate. The flow controller determines (process 3512) performance metrics based on the performance measurement and compares (process 3514) the performance metrics with respective acceptance levels which may be based on default values or defined in the upstream control data. If the performance is acceptable, the content-filtered video signal is encoded (process 3550) under the current permissible flow rate. If the performance is not acceptable, the flow controller either instructs an encoder to encode the content-filtered video signal at a lower flow rate (option 0, processes 3540, 3542) or communicate with a network controller to acquire a path of a higher capacity (option 1, processes 3540, 3544). The second option may not be selected if the traffic measurements indicate an unacceptable processing load at the client device.

The network interface also extracts (process 3520) data defining a preferred partial content of the full-content pure video signal and communicates the information to a content filter. The content filter extracts a new content-filtered signal (process 3522) from the pure video signal to generate a content-filtered video signal according to received definition of the new content. The flow controller determines (process 3524) a tentative flow-rate requirement corresponding to the new content. If the tentative flow rate does not exceed the current permissible flow rate (process 3526), the new content-filtered video signal is encoded (process 3550) under the permissible flow rate. Otherwise, the flow controller either instructs the encoder to encode the new content-filtered video signal encoded under constraint of the current permissible flow rate (option 0, processes 3540, 3542) or communicate with the network controller to acquire a path of a higher capacity (option 1, processes 3540, 3544).

FIG. 36 illustrates a flow-control system of a universal streaming server 120 comprising a flow controller 3610. The flow controller comprises a processor 3630 and a memory device storing instructions forming a module 3635 for determining a preferred flow rate. Module 3635 may implement processes 3500 of FIG. 35 . A server-network interface 3625 receives content-definition parameters 3612 and performance measurements 3616. A content filter 1120 receives a pure video signal 420 (FIG. 4 ) and extracts partial-content signal 3650 according to content-definition parameters 3612 of requested partial content received from an automaton 2545 (FIG. 25 ) associated with a client device. Module 3635 uses performance measurements 3616 received from the client device to determine a preferred flow rate. Encoder 3640 encodes the partial-content signal at the preferred flow rate and produces a compressed signal 3660 to be transmitted to the client device. Encoder 3640 comprises a transcoder and a server compression module (not illustrated).

At the universal streaming server 120, a received signal from a source may be decompressed to reproduce an original full-content signal; preferably a source sends signals compressed using lossless compression techniques. The full-content signal is processed in a content filter to produce a partial-content signal according to specified content-definition parameters. A preferred flow rate of the partial-content signal is determined based on either receiver performance measurements or network-performance measurements as will be described in further detail in FIG. 41 . Thus, the partial-content signal is encoded to produce a compressed partial content signal to be transmitted to a respective client device.

FIG. 37 illustrates a combined process 3700 of content filtering and flow-rate adaptation of a signal in the streaming system of FIG. 24 . The universal streaming server 120 continuously receives (process 3710) from client devices and associated automata control data from clients in the form of content-definition parameters and performance measurements. If the content-definition parameters from a client indicate a request to change content, the content-definition parameters are directed to a content filter 1120 (processes 3720 and 3760) and process 3710 is activated after imposing an artificial delay 3770 in order to ensure that received client's control data correspond to the changed signal content. Otherwise, if the content-definition parameters indicate maintaining a current content, the universal streaming server determines a preferred flow rate (process 3730). If the preferred flow rate is the same as a current flow rate, or has an insignificant deviation from the current flow rate, no action is taken and process 3710 is revisited (process 3740). If the preferred flow rate differs significantly from the current flow rate, the new flow rate is communicated to encoder 3640 (processes 3740 and 3750) and process 3710 is activated after an artificial delay 3770 to ensure that received client's control data correspond to the new flow rate. The artificial delay should exceed a round-trip delay between the universal streaming server and the client's device.

FIG. 38 illustrates a content filter 1120 of a universal streaming server. The content filter 1120 comprises a processor 3822, a buffer 3826 for holding data blocks of a pure video signal 420, and a memory device 3824 storing software instructions causing the processor to extract an updated content signal 3860 of partial content from buffered data blocks of the pure video signal. Blocks of the partial-content signal are stored in a buffer 3828. Processor 3822 executes software instructions which cause transfer of data in buffer 3828 to a subsequent processing stage which may include a transcoding module and/or a compression module.

Thus, the present invention provides a universal streaming server 120 comprising a network interface 1010, a content filter 1120, a flow controller 3610, and an encoder 3640.

The network interface is devised to receive a source video signal 900 from a panoramic signal source 110, content-definition parameters 3612, and performance measurements 3616 from a client device 180. A source signal-processing module 1024, which comprises a decompression module and a de-warping module, generates a pure video signal 420 from the source video signal 900. The pure video signal 420 is a full-coverage signal which corresponds to a respective scene captured at source

The content filter 1120 is devised to extract an updated content signal 3860 from the pure video signal 420 according to the content-definition parameters 3612. A processor of the content filter is devised to determine a ratio of size of the updated content signal to size of a current content signal.

The flow controller 3610 comprises a memory device storing flow-control instructions 3635 which cause a hardware processor 3630 to determine a current permissible flow rate of the partial-coverage signal based on the performance measurements and the ratio of size of the updated content signal to size of a current content signal.

The encoder 3640 comprises a transcoder module and a compression module and is devised to encode the partial-coverage signal under the current permissible flow rate.

The flow controller 3610 is devised to communicate with a network controller (not illustrated) to acquire a path compatible with a requisite flow rate between the universal streaming server 120 and the client device.

The flow-control instructions 3635 cause the hardware processor to retain an indication of a difference between the current permissible flow rate and a preceding permissible flow rate. If the difference exceeds a predefined threshold, the instructions cause the processor to delay the process of determining a succeeding permissible flow rate for a predefined delay period to ensure that the received performance measurements correspond to the current permissible flow rate.

The content filter 1120 comprises a respective processor 3822 and a respective memory device storing content-selection instructions 3824 which cause the respective processor to extract the updated content signal from the pure video signal 420. A first buffer 3826 holds Data blocks of the full-coverage video signal. A second buffer 3828 holds data blocks of the updated content signal 3860.

The content-selection instructions 3824 further cause the respective processor to determine the ratio of size of the updated content signal to size of a current content signal based on sizes of data blocks of the full-content signal and sizes of corresponding data blocks of the updated signal to be used in determining the current permissible flow rate.

The universal streaming server further comprises a frame-sampling module 1320 comprising a memory device storing frame-sampling instructions which cause a respective hardware processor to sample the pure video signal 420 during distant frame intervals to derive a frame-sampled video signal 1322 (FIG. 13 and FIG. 15 ). The frame intervals are selected so that the frame-sampled video signal has a constant flow rate not exceeding a nominal flow rate, and wherein the network interface is further devised to transmit the frame-sampled video signal to the client.

The content filter 1120 may be devised to derive a set of preselected content-filtered signals corresponding to different view regions from the full-content video signal. A compression module comprising a memory device storing signal-compression instructions may be devised to compress the preselected content-filtered signals to generate a succession of compressed content filtered signals occupying successive time windows. The network interface is further devised to transmit the succession of compressed content filtered signals to the client device, receive an indication of a preferred content-filtered signal of the set of preselected content-filtered signals, and communicate the indication to the content filter.

FIG. 39 illustrates initial processes 3900 performed at the universal streaming server 120 to start a streaming session. The universal streaming server receives a de-warped compressed full-content signal from a signal source (process 3910) and decompresses (process 3915) the full-content signal to produce a pure video signal corresponding to a respective scene captured at source. The server receives a connection request from a client device (process 3920); the request may include parameters of a partial-content of the signal. If the content-definition parameters are not provided, a default content selection is used (processes 3925, 3930). A content filter of the universal streaming server extracts (process 3940) a partial-content signal based on the default content selection or the specified partial-content selection. The initial content selection may be set to be the full content. A flow rate for the extracted signal may be specified in the connection request in which case an encoder of the universal streaming server may encode the signal under the constraint of the specified flow rate (processes 3950 and 3960). Otherwise, a default flow rate may be provided to the encoder (process 3955). A compressed encoded partial-content (or full-content) signal is transmitted to the target client device (process 3970).

FIG. 40 illustrates a method 4000 of adaptive modification of video-signal content and flow rate of the transmitted encoded signal. The universal streaming server receives (process 4010) a new content preference from an automaton (a person) associated with a client device. If the new content is the same as a current content (processes 4020 and 4050), a content filter of the universal streaming server maintains its previous setting and a preferred encoding rate based on received performance data is determined (process 4050, module 3635 of determining a preferred flow rate, FIG. 36 ). The signal is encoded at the preferred encoding rate (process 4060) and transmitted to the target client device (process 4070). If process 4020 determines that the new content differs from the current content, a content filter of the universal streaming server extracts a partial-content signal from the pure video signal (processes 4020 and 4030) and encodes the signal at a nominal flow rate (process 4040). A compressed encoded partial-content signal is transmitted to the target client device (process 4070).

FIG. 41 illustrates criteria 4100 of determining a preferred encoding rate of a signal based on performance measurements pertinent to receiver condition and network-path condition. A universal streaming server serving a number of client devices receives from a client device performance data relevant to the client's receiver condition and performance data relevant to a network path from the universal streaming server to the client's receiver. A module coupled to the universal streaming server determines primary metrics relevant to the receiver's condition and secondary metrics relevant to the network-path conditions. An acceptance interval, defined by a lower bound and an upper bound, is prescribed for each metric. The metrics are defined so that a value above a respective upper bound indicates unacceptable performance while a value below a respective lower bound indicates better performance than expected. A metric may be considered to be in one of three states: a state of “−1” if the value is below the lower bound of a respective acceptance interval, a state of “1” if the value is above a higher bound of the acceptance interval, and a state “0” otherwise, i.e., if the value is within the acceptance interval including the lower and higher bounds. The terms “metric state” and “metric index” are herein used synonymously.

The receiver's condition and the network-path condition are not mutually independent. The network path may affect data flow to the receiver due to delay jitter and/or data loss. The preferred encoding rate (hence flow rate) may be determined according to rules (i) to (iv) below.

-   -   (i) If any primary metric deviates from a respective predefined         acceptance interval indicating unacceptable receiver         performance, i.e., if a primary metric is above the predefined         acceptance interval, a new judicially reduced permissible         flow-rate (process 4120) is determined based on the primary         metrics regardless of the values of the secondary metrics.     -   (ii) If none of the primary metrics is above the predefined         acceptance interval and any secondary metric is above a         respective acceptance interval, a new judicially reduced         permissible encoding rate (process 4130) is determined based on         the secondary metrics.     -   (iii) If each primary metric is below a respective acceptance         interval and each secondary metric is below a respective         acceptance interval, a new higher permissible flow-rate (process         4140) may be judicially determined based on the primary and         secondary metrics.     -   (iv) If none of the conditions in (i), (ii), or (iii) above         applies, the current flow rate (encoding rate) remains unchanged         (4110).

FIG. 42 illustrates a method of determining a preferred encoding rate of a signal based on the criteria of FIG. 41 . The method details process 4050 of FIG. 40 . The method applies within a same video-signal content selection (view-region selection), i.e., when the universal streaming server determines that a current video-signal content is to remain unchanged until a request for video-signal content change is received.

A controller of a universal streaming server determines primary metrics based on performance data relevant to a client's receiver (process 4210). If any primary metric is above a respective acceptance interval, a judicially reduced permissible flow rate is determined based on the primary metrics (processes 4220 and 4225) and communicated (process 4280) to a respective encoder. Otherwise, with none of the primary metrics being above its respective acceptance interval, the controller of the universal streaming server determines secondary metrics based on performance data relevant to conditions of a network path from the universal streaming server to a client's device (processes 4220 and 4230).

If any secondary metric is above its predefined acceptance interval, a judicially reduced permissible flow rate is determined based on the secondary metrics (processes 4240 and 4245) and communicated (process 4280) to a respective encoder. Otherwise, if each primary metric is below its predefined acceptance interval and each secondary metric is below its predefined acceptance interval, a new encoding rate based on the primary and secondary metrics is determined (processes 4250 and 4260) and communicated to a respective encoder (process 4280). If any primary metric or any secondary metric is within its respective acceptance interval, the current encoding rate is maintained (process 4255).

Thus, the invention provides a method of signal streaming in a streaming system under flow-rate regulation. The method comprises acquiring at a server 120 comprising at least one hardware processor a source video signal 900 from which a pure video signal 420 is derived, sending a derivative of the pure video signal to a client device 180, and receiving at a controller 3610 of the server 120 content selection parameters 3612 from the client device defining preferred partial coverage of the full-coverage video signal. A content filter 1120 of the server extracts a partial-coverage video signal 3650 from the pure video signal 420 according to the content selection parameters 3612.

The server transmits the partial-coverage video signal to the client device 180. Upon receiving performance measurements 3616 pertinent to the partial-coverage video signal, the controller 3610 determines an updated permissible flow rate of the partial-coverage video signal based on the performance measurements. An encoder 3640 encodes the partial-coverage video signal according to the updated permissible flow rate. The encoder 3640 transcodes the partial-coverage video signal to generate a transcoded signal compatible with characteristics of the client device and compresses the transcoding signal.

The controller 3610 may instruct the encoder 3640 to encode the partial-coverage video signal under the constraint of a current permissible flow rate. Alternatively, the controller may communicate with a network controller (not illustrated) to acquire a downstream network path compatible with the updated permissible flow rate between the server 120 to the client device 180.

The derivative of the pure video signal may be generated as a frame-sampled video signal 1322 (FIG. 13 , FIG. 15 ) of a constant flow rate not exceeding a predefined nominal flow rate. Alternatively, the derivative may be generated as a compressed video signal 1342 (FIG. 13 ), within the predefined nominal flow rate, derived from the pure video signal 420. The derivative of the pure video signal may also be generated as a succession 1364 (FIG. 13 ) of compressed content-filtered video signals occupying successive time windows, and derived from the pure video signal.

The performance measurements pertain to conditions at a receiver of the client device and conditions of a downstream network path from the server to the client device. The controller 3610 determines primary metrics based on performance measurements pertinent to the conditions of the receiver. Where at least one primary metric is above a respective acceptance interval, the controller 3610 judicially reduces a current permissible flow rate based on the primary metrics (FIG. 41 ). Otherwise, where none of the primary metrics is above a respective acceptance interval, the controller 3610 determines secondary metrics based on performance measurements pertinent to the downstream network path. Where at least one secondary metric is above a respective acceptance interval, the controller judicially reduces the current flow rate of the signal based on values of the secondary metrics (FIG. 41 ).

Where each primary metric is below a respective acceptance interval and each secondary metric is below a respective acceptance interval, the controller judicially increases the current permissible flow rate based on the primary and secondary metrics (FIG. 41 ).

FIG. 43 illustrates a method of eliminating redundant processing of content selection in a universal streaming server 120 serving numerous clients. Upon receiving a full-coverage signal (process 4310) at the universal streaming server 120, a controller of the universal streaming server creates (process 4320) a register for holding parameters of produced partial-coverage signals (content-filtered signals). Initially, the register would be empty. A compressed full-coverage signal is decompressed at the server and de-warped if not de-warped at source. The controller receives (process 4330), from a specific client device, parameters defining a preferred view region. The controller inspects (process 4340) the register to ascertain presence or otherwise of a previously generated partial-coverage signal.

If the register content indicates that a matching partial-coverage signal has already been generated, the controller provides access to the matching partial-coverage signal (processes 4350 and 4360). A partial-coverage signal is directed to an encoder for further processing (process 4390). A partial-coverage signal may be directed to multiple encoders operating under different permissible flow rates to produce encoded signals of different flow rates with all encoded signals corresponding to a same view region. An encoder comprises a transcoding module and a server compression module. Alternatively, the partial-coverage signal may be presented to one encoder to sequentially produce encoded signals of different flow rates with all encoded signals corresponding to a same view region.

If no matching partial-coverage signal is found, the controller directs the full-coverage signal to a content filter 1120 (FIG. 36 ) to extract (process 4370) a new partial-coverage signal according to the new content-definition parameters defining the preferred view region. The new content-definition parameters are added (process 4380) to the register for future use and the new partial-coverage signal is directed to an encoder for further processing.

Thus, the invention provides a method of signal streaming comprising receiving at a server a full-coverage signal and at a controller comprising a hardware processor:

-   -   forming a register for holding identifiers of partial-coverage         signals derived from the full-coverage signal;     -   receiving from a client device coupled to the server new         content-definition parameters defining a view region; and     -   examining the register to ascertain presence of a matching         partial-coverage signal corresponding to the new         content-definition parameters.

If the matching partial-coverage signal is found, the matching partial-coverage signal is transmitted to the client device. Otherwise, the full-coverage signal is directed to a content filter for extracting a new partial-coverage signal according to the new content-definition parameters. The new partial-coverage video signal is encoded to generate an encoded video signal and a bit rate of the encoded video signal is determined. The new content-definition parameters are added to the register.

The process of encoding comprises transcoding the new partial-coverage video signal to generate a transcoded video signal then compressing the transcoded video signal under constraint of a predefined nominal flow rate.

The server receives from the client device performance measurements pertinent to conditions at a receiver of the client device and conditions of a network path from the server to the receiver. The controller determines performance metrics based on the performance measurements and a permissible flow rate. The permissible flow rate is determined as a function of deviation of the performance metrics from corresponding predefined thresholds and the bit rate of the encoded video signal.

The process of encoding may further direct the new partial-coverage signal to multiple encoders operating under different permissible flow rates to produce encoded signals of different flow rates corresponding to the view region.

Seamless Content Change

A universal streaming server 120 may access multiple panoramic multimedia sources 110 (FIG. 2 ) and may concurrently acquire multimedia signals to be processed and communicated to various client devices 180. Each multimedia signal may include a source video signal 900 (FIGS. 9, 17, 23, and 28 ) which may be a raw signal 312, a corrected signal 322, a compressed signal 342, or a compact signal 343 (FIG. 3 ). A source video signal is a full-coverage video signal which may be content filtered according to different sets of content-definition parameters to generate partial-coverage video signals corresponding to different view regions. The source video signal 900 may be decompressed and/or de-warped at the server to generate a pure video signal 420 which corresponds to a respective scene captured at source. The server 120 may employ multiple content filters 1120 as illustrated in FIGS. 17, 19, 28, and 29 .

Server 120 provides a content-filtered video signal specific to each active client device using a signal-editing module 460 comprising a content filter 1120, a transcoding module 1140, and a compression module 1160 (FIG. 11 ). The server may receive an upstream control signal from a specific client device 180 containing new content-definition parameters corresponding to a new view region. In order to provide seamless transition from one view region to another, the server may provide a number of spare signal-editing modules 460 so that while a particular signal-editing module 460-A is engaged in processing a current video-signal content, a free signal-editing module 460-B may process the video-signal content specified in a new content-definition parameters then replace the particular signal-editing module 460-A which then becomes a free signal-editing module.

FIG. 44 illustrates transient concurrent content-filtering of a video signal to enable seamless transition from one view region to another. A pure video signal 420 is presented to eight signal-editing modules 460, individually identified as 460(0) to 460(7). Six different content-filtered signals are generated from the pure-video signal to be distributed to at least six client devices 180. Signal-editing modules 460 of indices 0, 1, 2, 3, 5, and 7 are concurrently generating respective content-filtered video signals. Data blocks generated at the aforementioned signal-editing modules are respectively directed to buffers 4420 of indices 2, 0, 4, 1, 3, and 5. A multiplexer 4450 combines data blocks read from the buffers and the resulting multiple content-filtered streams 4460 are distributed to respective client devices through a network.

In the example of FIG. 44 , a client device 180 receiving a content-filtered video signal processed at signal-editing module 460(2) provides new content-definition parameters. A controller (not illustrated) comprising a hardware processor instructs signal-editing module 460(6), which is currently free, to generate a new content-filtered video signal according to the new content-definition parameters. After a transient period, signal-editing module 460(6) would direct data blocks of the new content-filtered video signal to buffer 4420(4) and signal-editing module 460(2) would disconnect and become a spare signal-editing module.

FIG. 45 illustrates coupling the universal streaming server 120 to a network. The universal streaming server 120 may be implemented in its entirety within a cloud computing network and communication with the client devices 180 may also take place within the cloud computing network. Alternatively, the generated client bound streams 940 (FIG. 9 ) may be routed to the client devices through a router/switch 4540 of another network. Router-switch 4540 may connect to numerous other servers or other router-switches through input ports 4541 and output ports 4542.

Thus, the server comprises network access ports to communicate with a plurality of video sources and a plurality of client devices through a shared network. The server may be partially or entirely installed within a shared cloud-computing network where the physical processors and associated memory devices are dynamically allocated on demand.

Summing up, the disclosed universal streaming server is devised to interact with multiple panoramic multimedia sources of different types and with client devices of different capabilities. The server may exchange control signals with a panoramic multimedia source to enable acquisition of multimedia signals together with descriptors of the multimedia signals and data indicating signal processes performed at source. The server may exchange control signals with a client device to coordinate delivery of a signal sample of a full-coverage (attainable-coverage) panoramic video signal and acquire identifiers of a preferred view region from a viewer at the client device.

The server is devised to implement several methods of capturing a client's viewing preference. According to one method, a signal sample corresponding to attainable spatial coverage is sent to client device and a viewer at a client device may send an identifier of a preferred view region to the server. The server then sends a corresponding content-filtered video signal. The server distributes software module to subtending client devices to enable this process. According to another method, the server may multicast to client devices a number of content-filtered video signals corresponding to different view regions. The content-filtered video signals are derived from a full-coverage (attainable-coverage) panoramic video signal. Viewers at the client devices may individually signal their respective selection. The server may use a streaming-control table (FIG. 32 ) to eliminate redundant processing.

A panoramic video signal is acquired and transcoded to produce a transcoded signal compatible with a client device. A signal sample of the transcoded signal is then transmitted to the client device. Upon receiving from the client device descriptors of a preferred view region, the content of the transcoded signal is edited to produce a content-filtered signal corresponding to the preferred view region. The content-filtered signal, or a compressed form of the content-filtered signal, is sent to the client device instead of the signal sample.

Acquiring the panoramic video signal comprises processes of establishing a connection from the server to a panoramic multimedia source, requesting and receiving a multimedia signal that includes the panoramic video signal together with indications of any signal processing applied to the panoramic video signal at source. The acquired panoramic video signal may be decompressed and/or de-warped at the server according to the indications of processes performed at source. The signal sample may be a frame-sampled signal comprising distant frames of the transcoded signal. Alternatively, the signal sample may be a compressed form of the transcoded signal.

Arrangements for efficient video-signal content selection in a universal streaming system serving numerous clients have been described and illustrated in FIGS. 19, 28, 29, and 43 . The method of signal streaming of FIG. 43 comprises receiving (process 4310) at a server 120 a full-coverage signal and at a controller comprising a hardware processor:

-   -   forming (process 4320) a register for holding identifiers of         partial-coverage signals derived from the full-coverage signal;     -   receiving (process 4330) from a client device 180 coupled to the         server 120 new content-definition parameters defining a view         region; and     -   examining (process 4340) the register to ascertain presence of a         matching partial-coverage signal corresponding to the new         content-definition parameters.

If a matching partial-coverage signal is found (processes 4350 and 4360) the controller directs (process 4390) the matching partial-coverage signal to an encoder prior to transmission to the client device. If a matching partial-coverage signal is not found, the controller directs (process 4350) the full-coverage signal to a content filter to extract (process 4370) a new partial-coverage signal according to the new content-definition parameters.

The new partial-coverage video signal may need to be transcoded to generate a transcoded video signal compatible with characteristics of the client device. The transcoded video signal may be further compressed under a predefined nominal flow rate. The controller determines a bit rate of the encoded video signal and inserts (process 4380) the new content-definition parameters in the register.

The method further comprises receiving from the client device performance measurements pertinent to conditions at a receiver of the client device and conditions of a network path from the server to the receiver. The controller determines performance metrics based on the performance measurements. The controller determines a permissible flow rate as a function of deviation of the performance metrics from corresponding predefined thresholds (FIG. 41 ) and the bit rate of the encoded video signal.

The new partial-coverage signal may be directed to multiple encoders operating under different permissible flow rates to produce encoded signals corresponding to the same view region but of different flow rates and/or different formats to be transmitted to different client devices.

Processor-executable instructions causing respective hardware processors to implement the processes described above may be stored in processor-readable media such as floppy disks, hard disks, optical disks, Flash ROMS, non-volatile ROM, and RAM. A variety of processors, such as microprocessors, digital signal processors, and gate arrays, may be employed.

FIG. 46 illustrates a conventional system 4600 for selective content broadcasting. A plurality of signal sources 4610 is positioned for live coverage of an event. Each signal source 4610 comprises a camera 4614 operated by a person 4612 and coupled to a transmitter 4616. The signals from the signal sources 4610 are communicated through a transmission medium 4620 to a broadcasting station. A receiver 4630 at the broadcasting station acquires the baseband signals 4640. The receiver 4630 has multiple output channels each for carrying a baseband signal 4640 generated at a respective signal source 4610. Each acquired baseband signal is fed to a respective display device 4650 of a plurality of display devices. A manually operated view-selection unit 4660 selects one of baseband signals fed to the display devices 4650. A viewer 4662 observes all displays and uses a selector (a “switcher”) 4664 to direct a preferred baseband signal 4640 to a transmitter 4680. The transmitter 4680 is coupled to a transmission medium through an antenna or a cable 4690. Components such as encoders and decoders, well known in the art, used for performing baseband signal compression and decompression, are omitted in FIG. 46 .

The panoramic multimedia source may use a panoramic camera that does not provide depth indications, or an RGB camera (referenced as RGB-D camera) that uses a depth sensing device to provide depth information (distance to sensors) for each pixel.

The objective is a system for selective video-content dissemination where partial content of a full-content panoramic video signal, capturing a panoramic view, is dynamically extracted and communicated to broadcasting stations and/or streaming servers. The system may employ programmable VR headset with gaze-sensing capability. Several techniques for determining parameters defining a human gaze have been developed, and are continuously being enhanced, using infrared sensors.

FIG. 47 illustrates an arrangement for broadcasting operator-defined content of multimedia signals. A panoramic signal source 4710 generates a modulated carrier source signal 4712 containing a panoramic multimedia signal. The panoramic multimedia signal includes a 4π video signal component from a 4π camera as well as other components, such as audio and text components, which may be produced by camera circuitry and/or other devices (not illustrated). A raw video signal 312 (FIG. 3 ) provided by the camera may be inherently warped. A source-processing unit 4714 may perform processes including:

-   -   de-warping the raw signal to produce a corrected signal 322         (FIG. 3 );     -   compressing the raw signal without de-warping to produce a         compressed signal 342 which would be decompressed and de-warped         at destination;     -   de-warping and compressing the raw signal to produce a compact         signal 343 which would be decompressed at destination.

The source-processing unit 4714 may further insert signal description data indicating whether any signal process (de-warping/compression) has been performed The source-processing unit 4714 may also include a module 4715 for providing cyclic video-frame numbers where the sequential order of the frames may be indicated. For example, using a single byte of 8 bits to mark the sequential order, the frames would be cyclically indexed as 0 to 255. This indexing facilitates content filtering.

A broadband transmitter 4716 transmits the processed multimedia signals along a transmission medium 4718 to a content selector 4740 for content filtering before communicating the signal to a broadcasting facility.

An acquisition module 4720 generates from the modulated carrier source signal 4712 a pure multimedia signal 4730 as well as a signal descriptor 4732. The pure multimedia signal 4730 includes a pure video signal that represents images captured by the camera. The signal descriptor 4732 identifies processes performed at the panoramic signal source 4710. The pure multimedia signal is presented to a content selector 4740, to be described below with reference to FIG. 50 , to produce a content-filtered signal 4764. The content selector 4740 comprises a virtual-reality (VR) headset 4750 and a content filter 4760. An operator 4725 uses the VR headset to select content considered suitable for target viewers. The operator may rely on an internal display of the VR headset and/or an external display 4770.

FIG. 48 illustrates a first combined broadcasting and streaming system 4800 configured to receive a modulated carrier source signal 4712 and generate an operator-defined content filtered multimedia signal as well as multiple viewer-defined content-filtered multimedia signals.

A 4π multimedia baseband signal is generated at a multimedia signal source 4710 (FIG. 47 ) which modulates a carrier signal to produce the modulated carrier source signal 4712. The received modulated carrier source signal 4712 is directed concurrently to a broadcasting subsystem 4804 and a streaming subsection 4808.

A repeater 4810 may enhance the modulated carrier source signal 4712 and direct the enhanced carrier signal to a streaming apparatus 4820 through a transmission medium 4812. The streaming apparatus 4820 comprises an acquisition module 4720-B and a Universal Streaming Server 120. The Universal Streaming Server 120 receives viewing-preference indications from a plurality of client devices 180 through network 150 and provides client-specific multimedia signals as described earlier with reference to FIGS. 10, 28, and 29 .

An acquisition module 4720-A generates a pure multimedia signal 4730, which corresponds to the content captured at a field of an event, from the modulated carrier source signal 4712. The pure multimedia signal 4730 is directed to content selector 4740 which continually extracts content-filtered signal 4764 to be communicated to a broadcasting facility. The broadcast content-filtered signal 4764 may be compressed at compression module 4862 to produce compressed content-filtered signal 4864 which is supplied to transmitter 4870 for transmitting a respective modulated carrier through a channel 4880 to a broadcasting station and/or to the Universal Streaming Server 120 through a channel 4890 and network 150. The Universal Streaming Server 120 may offer the broadcast multimedia signal as a default for a client 180 that does not specify a viewing region preference.

FIG. 49 illustrates an acquisition module 4720 for reconstructing a pure multimedia signal from a modulated carrier source signal 4712 received from a panoramic multimedia signal source. The pure multimedia signal contains a pure video signal and other multimedia components. As illustrated in FIG. 3 , the baseband signal transmitted from a multimedia source may be a raw signal 312, a corrected (de-warped) signal 322 which is a pure multimedia signal, a compressed raw signal 342, or a compact signal (de-warped and compressed) 343. Thus, the received modulated carrier source signal 4712 may carry one of the four baseband signals 312, 322, 342, and 343.

A receiver 4940 demodulates the modulated carrier source signal 4712 and produces a source multimedia signal 4943 and a signal descriptor 4732 which identifies processes performed at source. Input selector 4946 directs the source multimedia signal 4943 to different paths to output of the acquisition module. Output selector 4947 is synchronized with, and complements, input selector 4946.

Receiver 4940 produces:

-   -   (a) a replica of a raw signal 312 which is supplied to pure         signal generator 4950-A comprising a de-warping module 320 to         produce a pure multimedia signal 4730;     -   (b) a corrected signal 322 (de-warped) which is a pure         multimedia signal 4730;     -   (c) a compressed signal 342 which is supplied to pure signal         generator 4950-B comprising a decompression module 350 and a         de-warping module 320 to produce a pure multimedia signal 4730;         or     -   (d) a compact signal 343 (de-warped and compressed) which is         supplied to pure-signal generator 4950-C comprising a         decompression module 350 to produce a pure multimedia signal         4730.

FIG. 50 illustrates an arrangement for content selection for broadcasting comprising a virtual-reality headset (VR headset) 4750 and a content filter 4760. The VR headset comprises at least one processor, storage media, and a gaze-tracking mechanism.

In a first implementation of the content selector (4740-A), a content-filter 4760A is a separate hardware entity and a pure multimedia signal 4730 is supplied to both the VR headset 4750 and the content filter 4760A. The content filter 4760A comprises a respective processor and a memory device storing processor-readable instructions constituting a module for extracting from the pure multimedia signal a filtered multimedia signal with adaptive spatial coverage which closely corresponds to head or eye movement of an operator using a low-latency VR headset 4750. A control signal 4752 communicates parameters defining the spatial coverage from the VR-headset 4750 to the content filter 4760A. The content filter 4760A generates content-filtered signal 4764 intended for broadcasting. The content-filtered signal 4764 may be displayed using an external display 5090.

In a second implementation of the content selector (4740-B), a content-filter 4760B is embedded in the VR headset 4750 where processor-readable instructions for extracting a filtered multimedia signal reside in a memory device of the VR headset. Thus, the content-filtered signal is provided at an outlet of the VR headset 4750.

FIG. 51 illustrates a first broadcasting subsystem 5100 for selective content broadcasting employing a panoramic camera and a VR headset. Instead of deploying multiple signal sources 4610 (FIG. 46 ), a single, possibly unattended, panoramic signal source 4710 may be used to cover an event. A 4π camera 310 captures a view and produces a raw signal 312 which may be directly fed to a broadband transmitter 4716. Alternatively, the raw signal may be fed to a source-processing unit 4714 which selectively produces a corrected (de-warped) signal 322, a compressed raw signal 342, or a compact signal (de-warped and compressed) 343 as illustrated in FIG. 3 . The output of the source-processing unit 4714 is supplied to broadband transmitter 4716.

The broadband transmitter 4716 sends a modulated carrier source signal 4712 through transmission medium 4718 to an acquisition module 4720 which is a hardware entity comprising a receiver 4940, a processor residing in a monitoring facility 5120, and memory devices storing processor-readable instructions which cause the processor to perform functions of de-warping and/or decompression as illustrated in FIG. 3 . The acquisition module produces a pure multimedia signal 4730 which is fed to a VR headset 4750 and a content filter 4760 (FIG. 50 ). The pure multimedia signal 4730 is also fed to a panoramic-display device 4770 if the VR headset does not have an internal display unit or to provide a preferred display. As described above, the view-selection unit 4740 comprises a VR headset 4750 which an operator 4725 wears to track views of the panoramic display considered to be of interest to television viewers of an event.

A low-latency VR headset 4750 interacting with a content filter 4760 generates a content-filtered multimedia signal 4764 corresponding to the operator's changing angle of viewing. The content-filtered multimedia signal may be supplied to an auxiliary display device 5090 and to a compression module 4862. The output signal 4864 of the compression module is fed to a transmitter 4870 to modulate a carrier signal to be sent along a channel 4880 to a broadcasting station and—optionally—along a channel 4890 to a Universal Streaming Server 120.

In the broadcasting subsystem of FIG. 51 , the content selector 4740 residing in a monitoring facility 5120, which is preferably situated at a short distance from the panoramic signal source 4710, comprises a VR headset and a content filter 4760. The VR headset, together with the operator, constitutes a “content controller”. The content filter 4760 is either directly coupled to the VR headset 4750 or embedded in the VR headset. The control data 4752 generated at the VR headset corresponds to a pure signal 4730 supplied to the VR headset.

Relating Control Data to Content Data

The system relies on video-frame indices in order to relate content data of each video frame to corresponding control data, which include view-region definition data.

FIG. 52 illustrates a second system 5200 for generating operator-defined content where the VR headset 4750 and the content filter 4760 are not collocated so that a signal-transfer delay from the acquisition module 4720 to the content filter 4760 may differ significantly from the signal transfer delay from the acquisition module 4720 to the VR headset 4750. Due to the signal-transfer delay, a content-filtered signal produced at the content filter based on control data sent from the VR headset may result in a view region that differs from a view region that the operator of the VR headset selects.

It is noted that the system of FIG. 47 or FIG. 52 may be partially implemented within a cloud-computing facility.

FIG. 53 illustrates main components of the view adaptor of FIG. 52 . The view adaptor receives frames of pure signal 4730 from an acquisition module 4720 and control data 5260 from the VR headset of the distant content selector 5240 to produce content filtered signal 5280. To avoid the discrepancy, a circular content buffer 5330, preceding the content filter 4760, as illustrated in FIG. 53 , is used to hold content data of a sufficient number of frames of the pure signal 4730. A content-filter controller 5320 coupled to the circular content buffer and to the content filter 4760 receives control data comprising a view-region definition and a respective frame index 5322 from the distant VR headset. The content-filter controller 5320 reads frame data of the respective frame index from the circular buffer then presents the frame data together with the view-region definition to content filter 4760 which produces a content-filtered signal 4764 to be forwarded for broadcasting or data streaming. The circular buffer 5330, the content-filter controller 5320, and the content filter 4760 form a view adaptor 5210.

Data blocks of a pure signal 4730 derived at an acquisition module 4720 collocated with the view adaptor 5210 (FIG. 52 ) are stored in the circular content buffer 5330 and simultaneously directed to a communication channel 5220, through a transmitter 5221 and a network 5226, to the distant VR headset 4750. The circular content buffer stores data blocks, each data block corresponding to a frame, i.e., pure signal data during a frame period (for example, 20 milliseconds at a frame rate of 50 frames per second). Each data block is stored at a buffer address corresponding to a cyclic frame number. For example, the circular content buffer may be organized into L segments, L>1, each for holding a data block of one frame. The L segments would be indexed as 0 to (L−1). The frames are assigned cyclical numbers between 0 and (Γ−1), Γ≥L. F is preferably selected as an integer multiple of L so that a data block corresponding to frame M would be stored in memory segment of index m, m=M_(modulo L), in cyclical content buffer 5330. For example, with L=128 and Γ=16384, a data block of a frame of index 12000 would be stored at address (12000 _(modulo 128)); that is 96.

At a frame rate of 50 frames per second, the duration of 128 frames is 2.56 seconds which would be much larger than a round-trip signal transfer delay between the view adaptor 5210 and the distant VR headset 4750. Thus, each data block would be held in the content buffer for a sufficient period of time to be presented together with corresponding control data to the content filter 4760 of view adaptor 5210 (FIG. 53 ). This requires that each control signal resulting from an operator's action be associated with a respective cyclic frame number.

As illustrated in FIG. 47 , a module 4715 of the panoramic signal source 4710 provides cyclic video-frame numbers which would be needed to facilitate relating control data (messages) 5260 (FIG. 52 ), received at view adaptor 5210 from distant VR headset 4750, to corresponding video frames. If the panoramic signal source 4710 does not provide frame indices, a module (not illustrate) for inserting in each frame data block of pure signal 4730 a respective cyclic frame index may be incorporated within the acquisition module 4720.

As mentioned above, the cyclic period, denoted Γ, of the cyclic video-frame numbers is at least equal to L and may be much larger. With Γ=16384 and L=128, for example, a frame of an absolute frame number 12000 would have a cyclic number of 20192|modulo 16384, which is 3808, with respect to cyclic period r and a cyclic number 20192|modulo 128, which is 96, with respect to cyclic period L. Content-filter controller 5320 would then determine the address of a frame data block corresponding to frame cyclic number 3808 as 3808|modulo 128, which is 96.

FIG. 54 details the view adaptor 5210. Acquisition-module interface 5412 comprises stored software instructions which cause processor 5450 to receive signal 4730 from the acquisition module 4720 organized into frame data blocks to be stored in circular 5330 under control of content-filter controller 5320. Acquisition-module interface 5412 detects individual frame indices 5322 which may be generated at the acquisition module 4720 or at signal source 4710. The frame indices are cyclical numbers as described above. VR-interface 5416 comprises software instructions which cause processor 5450 to receive control data 5260, which includes view-region definition 5324, from the VR headset of the distant content selector 5240.

Content-filter controller 5320 comprises stored software instructions which cause processor 5450 to store frame data blocks in the circular content-buffer 5330 according to frame indices 5322, retrieve selected frame data blocks 5332 from the circular-content buffer.

Content filter 4760 comprises software instructions which cause processor 5450 filter to extract content-filtered signal 5280 from a selected frame data block and store the content-filtered signal 5280 in a memory device 5470.

Content-filter controller 5320 may also comprise software instructions which cause processor 5450 to perform conventional signal-processing functions, such as formatting and/or compressing content-filtered signals and/or compressing the content-filtered signals stored in memory 5470 before directing the produced signals to transmitter 5490 for dissemination to a broadcasting station and/or a streaming server.

Regulating View-Region Updates

FIG. 55 illustrates control data (view-region definition data) 5260 sent from the distant VR headset 4750 to the view adaptor 5210 of the system of FIG. 52 . The control data comprises view-region definition data such as the conventional parameters “Pan-Tilt-Zoom” (PTZ) defining a “gaze position” 5520 and other parameters which enable precise definition of a view region corresponding to the operator's gaze orientation. In order to relate the parameters to an appropriate portion of the pure signal 4730, an identifier of a corresponding frame need be included in the control data 5260. It suffices to use cyclic frame numbers. As illustrated in FIG. 55 , a cyclic frame number is associated with each gaze position. With Γ=16384, a frame cyclic number 0 follows a frame cyclic number 16383. Cyclic period Γ may be equal to or an integer multiple of the number L of buffer segments of the cyclic content buffer 5330. The control data from the distant VR headset to the view adaptor 5210 indicates a gaze position, a corresponding frame index, and other associated parameters.

In order to avoid unnecessary redefinition of the view region for minor displacements of the gaze position, herein referenced as gaze-position jitter, a displacement 5530, denoted Δ, of a current gaze position from a reference gaze position defining a last view region is determined. The displacement may be determined at the VR headset or at the content filter 5320 of the view adaptor 5210. The displacement may be determined as a Euclidean distance between a current gaze position and a reference gaze position or as a sum of absolute values of shifts of coordinate values defining the gaze position. In the example of FIG. 55 , the displacement is determined as the sum of absolute shifts of coordinates. Other measures for determining displacements may be used.

If the displacement exceeds a predefined displacement threshold Δ*, a new view region is determined at the content-filter controller 5320 and the current gaze position becomes the reference gaze position (reference 5540). Otherwise, if the displacement is less than, or equal, to the predefined threshold Δ*, the last reference gaze position remains in effect.

If the displacement is determined at the VR headset, the control data from the distant VR headset may also include a “refresh” flag if the displacement exceeds Δ*. Otherwise, the control data may include a “no-change flag” so that the last reference gaze position remains in effect. A refresh flag is an instruction to the content-filter controller 5320 of the view adaptor 5210, to redefine the view region.

As illustrated in FIG. 55 , a tuple {40, 60, 20} defines a gaze position corresponding to cyclic frame index 16350. The displacement measure from a previously filtered frame is 11 units. With a predefined threshold Δ* of 9.0, a new view region corresponding to frame 16350 and a predefined boundary shape is determined at the content filter 4760 of the view adaptor 5210.

The displacement of gaze positions during 55 frame periods following frame 16350 is determined to be insignificant (below a predefined threshold value). For example, a tuple {42, 56, 2} defines a gaze position corresponding to cyclic frame index 16383. The displacement from the previously filtered frame, of index 16350, determined as the sum of absolute values of shifts of coordinate values (|42−40|+|56−60|+|21−20|), which is 7, is less than the threshold, hence, the previous view region remains unchanged.

A tuple {41, 58, 21} defines a gaze position corresponding to cyclic frame index 0. The displacement from the previously filtered frame, of index 16350, determined as the sum of absolute values of shifts of coordinate values (|41−40|+|58−60|+|21−20|), which is 4, is less than the threshold, hence, the previous view region remains unchanged.

A tuple {37, 68, 17} defines a gaze position corresponding to cyclic frame index 21. The displacement from the previously filtered frame, of index 16350, determined as the sum of absolute values of shifts of coordinate values (|37−40|+|68−60|+|17−20|), which is 14, exceeds the predefined threshold. Hence, a new view region corresponding to frame 21 and the predefined boundary shape is determined at the content filter 4760 of the view adaptor 5210.

As illustrated, redefinitions of the view region correspond to frames 16350, 21, and 50. The view region corresponding to frame 16350 remains in effect for a period of 55 frames (determined as (21-16350)_(modulo 16384)). The view region corresponding to frame 21 remains in effect for a period of 29 frames (determined as (50-21)|modulo 16384).

Video Frame Versus Time Indications

The content controller communicates gaze positions and corresponding video-frame indices. The VR headset does not communicate video-frame content (in fact, it may not even have the content of each video-frame if the option of “frame-sampling” is activated). In contrast, a casting VR headset communicates contents of all video frames displayed at the casting VR headset to an external device (such as a mobile phone).

FIG. 56 illustrates data flow 5600 within the first system 4700 of producing operator-defined content, including content data 5610 transmitted to the VR headset and control data 5690 transmitted from the VR headset. Acquisition module 4720 is collocated with the VR headset 4750 and the content filter 4760 (FIG. 47 ). The acquisition module generates a pure multimedia signal 4730 from source signal 4712 and concurrently supplies consecutive frame data blocks 5630, each frame data block comprising content of a respective frame, to the VR headset 4750 and the content filter 4760. The cyclic frame identifiers 5620 of frame data blocks of a pure signal 4730 supplied to the VR headset 4750 and the content filter 4760 are denoted f_(j), j≥0; only f₀ to f₉ are illustrated. The frame identifier f_(j), j≥0, has values between 0 and (Γ−1) where Γ is a sufficiently large integer as described earlier; thus, f_(j)=j_(modulo Γ). The time instants t₀, t₁, . . . t₉ correspond to completion of transmission of frames f₀, f₁, . . . f₉, respectively. A displayed image corresponding to the frame data block may result in a response from the operator 4725 causing the tracking mechanism of the VR headset to generate a new gaze position with latency 5650 following a gaze-detection instant 5635. Three gaze-detection instants, 5635(0), 5635(1), and 5635(2), are illustrated.

Control data from the VR headset 4750 to the content filter 4760 indicating a gaze-position is inserted in the control signal 4752. The control data may also include a frame identifier and other control parameters defining a view region. The control data may be sent upon detection of a change of gaze position or sent periodically. In the example of FIG. 56 , a periodic control-data message 5640 is sent every frame period, after a processing delay δ*, following receiving each frame data 5630. Each message 5640 includes a frame identifier 5660, denoted ϕ, j≥0, and a corresponding gaze position. A frame identifier ϕ, j≥0, received at the content filter 4760 from the VT headset 4750 corresponds to a frame index f_(j). Thus, frame identifier ϕ, j≥0, are cyclic having values between 0 and (Γ−1), i.e., ϕ_(j)=j_(modulo Γ).

Accounting for Control-Data Delay

FIG. 57 illustrates control-data flow 5700 within the second system 5200 of producing operator-defined content. Pure multimedia data 4730 generated at acquisition module 4720 is supplied to the circular content buffer 5330 and transmitted to the distant VR headset 4750. The cyclic frame identifiers of frame data blocks 5730 of a pure signal 4730 supplied to the circular content buffer 5330 and the distant VR headset are integers denoted f_(j), j≥0, f_(j)=j_(modulo Γ); only f₀ to f₉ are illustrated. The time instants t₀, t₁, . . . t₉ correspond to completion of transmission of frames f₀, f₁, . . . f₉, respectively. Each frame data blocks 5730 sent from an acquisition module 4720 collocated with the view adaptor to the distant VR headset 4750 is subject to a transfer delay 5722. A displayed image corresponding to the frame data block may result in a response from the operator 4725 causing the tracking mechanism of the VR headset to generate a new gaze position with latency 5750. A control message 5740 indicating a gaze-position is inserted in the content control data 5260 which is sent to the view adaptor 5210. The control message 5740 experiences a transfer delay of 5724. The control message 5740 also includes a frame identifier and other control parameters defining a view region.

The content control data 5260 may be sent upon detection of a change of gaze position or sent periodically. In the example of FIG. 57 , a control message 5740 is sent every frame period, after a processing delay δ* following receiving each frame data. The control message 5740 sent every frame period includes a frame index and a corresponding gaze position.

The total round-trip and processing delay may be significantly larger than the frame period 5725 depending on the distance between the view adaptor 5210 and the distant VR headset. In the illustrated example, a first message 5740, sent after a processing delay δ* following receiving content data of frame f₀, does not correspond to frame f₀ and indicates a null frame ϕ* (reference 5745) and a default gaze position. The VR headset generates a gaze position after a delay 5750 following a first gaze-detection instant 5735(0) which occurs after the VR headset receives content data of frame f₁.

The frame identifiers indicated in the messages 5740 are denoted ϕ_(j), j≥0; only ϕ₀ to ϕ₅ are illustrated. As indicated, there is a delay of approximately 3.4 frame periods between the instant of sending a frame data block 5710 from an acquisition module coupled to the view adaptor 5210 and receiving a respective control message 5740 from the distant VR headset. At time instant t₅, frame data block f₅ is already stored in the circular content buffer 5330 and control data relevant to a frame f₀ sent earlier has been received at content-filter controller 5320 of the view adaptor 5210. Thus, the circular content buffer should have a capacity to store content of at least 6 frames.

FIG. 58 illustrates another example of control-data flow 5800 within the second system 5200 of producing operator-defined content for a case of large round-trip transfer delay between the view adaptor 5210 and the distant VR headset. The cyclic frame identifiers of frame data blocks 5830 of a pure signal 4730 supplied to the circular content buffer 5330 and the distant VR headset are integers denoted f_(j), j≥0, f_(j)=j_(modulo Γ); only f₀ to f₁₅ are illustrated. The time instants t₀, t₁, . . . t₁₅ correspond to completion of transmission of frames f₀, f₁, . . . f₁₅, respectively. Each frame data blocks 5830 sent from an acquisition module 4720 collocated with the view adaptor to the distant VR headset 4750 is subject to a transfer delay 5822. A displayed image corresponding to the frame data block may result in a response from the operator 4725 causing the tracking mechanism of the VR headset to generate a new gaze position with latency 5850. A control message 5840(k), k≥0, indicating a gaze-position corresponding to frame data 5830 of a frame of index k, is inserted in the content control data 5260 which is sent to the view adaptor 5210. The control message 5840 experiences a transfer delay of 5824. The control message 5840 also includes a frame identifier and other control parameters defining a view region.

A control message 5840, including a frame index and a corresponding gaze position, is sent from the VR headset to the content-filter controller 5320 every frame period, after a processing delay δ* following receiving each frame data.

The total round-trip and processing delay approximately equals 8.3 frame periods 5825. In the illustrated example, a first message 5840, sent after a processing delay δ* following receiving content data of frame f₀, does not correspond to frame f₀ and indicates a null frame ϕ* (reference 5845) and a default gaze position. The VR headset generates a gaze position after a delay 5850 following a first gaze-detection instant 5835(0) which occurs after the VR headset receives content data of frame f₁.

The frame identifiers indicated in the messages 5840 are denoted ϕ_(j), j≥0; only ϕ₀ to ϕ₉ are illustrated. As indicated, there is a delay of approximately 8.3 frame periods between the instant of sending a frame data block 5810 from an acquisition module coupled to the view adaptor 5210 and receiving a respective control message 5840 from the distant VR headset. At time instant t₁₀, frame data block f₁₀ is already stored in the circular content buffer 5330 and control data relevant to a frame f₀ sent earlier has been received (frame identifier ϕ₀) at content-filter controller 5320 of the view adaptor 5210. Thus, the circular content buffer should have a capacity to store content of at least 11 frames.

In accordance with an embodiment of the present invention, a register, for holding indications of a frame index of the most recent frame data block received from acquisition module 4720 and the most recently detected gaze position, is installed within, or coupled to, the VR headset. A control message 5840(k), k≥0, includes content of the register.

As illustrated in FIG. 57 , a control message 5740(k), k≥0, includes content of the register. Control messages 5740(0) and 5740(1) correspond to the gaze position corresponding to gaze-detection instant 5735(0) and include a same Pan-Tilt-Zoom values, denoted PTZ₀. Control messages 5740(2) to 5740(5) correspond to the gaze position corresponding to a subsequent gaze-detection instant 5735(1) and include a same Pan-Tilt-Zoom values, denoted PTZ₁.

As illustrated in FIG. 58 , with no updating of gaze position for a period of four frames, control messages 5840(0) to 5840(3) correspond to the gaze position corresponding to gaze-detection instant 5835(0) and include a same Pan-Tilt-Zoom values, denoted PTZ₃. Likewise, with no updating of gaze position for a period of four frames, control messages 5840(4) to 5840(7) correspond to the gaze position corresponding to a subsequent gaze-detection instant (not illustrated) and include a same Pan-Tilt-Zoom values, denoted PTZ₄.

FIG. 59 illustrates determining a gaze position at a VR headset. A current frame index 5950 is inserted in the panoramic pure multimedia signal 4730 either at the panoramic signal source 4710 (reference 4715) or at the acquisition module 4720. The VR headset 4750 comprises, amongst other components, a gaze sensor 5950 and an internal display screen 5930. A gaze position translation module 5960 coupled to the VR headset provides PTZ coordinates corresponding to a specific frame and a specific point of the frame. Values of the PTZ coordinates are included in control data 5260 sent to the view adaptor 5210 through transmitter 5261 and communication path 5250.

FIG. 60 illustrates updating frame-data content 6000 within circular content buffer 5330 of the view adaptor 5210 indicating occupancy of the content buffer during successive frame periods. A memory address 6020 of each frame data block 6010 stored in content buffer 5230 is indicated. As described above, content buffer 5330 is a circular buffer that stores a maximum of L frame data blocks, L>1, each frame-data block occupying one buffer segment. The number L may be selected so that the duration of L frames exceeds the round-trip data transfer delay between the view adaptor 5210 and the distant VR headset 4750. Frame data blocks are written sequentially in consecutive buffer segments of indices 0 to (L−1). The buffer segment in which a frame-data block is written during a frame period j is denoted W(j) and the buffer segment from which a frame-data block is read during a frame period k is denoted R(k), j≥0, k≥0. With a frame rate of 50 frames per second, for example, storing 128 most recent frames (L=128) is adequate for a round-trip delay, between the view adaptor 5210 and the distant VR headset 4750, of up to 2.56 seconds, which is significantly larger than an expected round-trip delay. In the illustrated case, L is selected to equal only 8 for ease of illustration.

Consecutive frame data blocks of the pure signal 4730 at output of the acquisition module collocated with the view adaptor 5210 are denoted A0, A1, . . . , etc., where A0 is the first frame-data block of the pure signal 4730 of a specific video stream. The buffer segments are referenced as segment-0, segment-1, . . . , and segment-7. During the first frame period, frame-data block A0 is written in segment W(0). During the second frame period, frame-data block A1 is written in segment W(1), and so on. During a fifth frame period, frame data block A0 is read from segment R(0). During a sixth frame period, frame data block A1 is read from segment R(1). An underlined notation of a frame data block indicates that the data block has been read and may be overwritten.

During an eighth frame period, frame-data block A8 is written in segment-0 (8_(modulo L)=0), overwriting A0, during a ninth frame period, frame-data block A9 is written in segment-1 (9_(modulo L)=1), overwriting A1, and so on. With a round-trip transfer delay not exceeding eight frame periods, eight frame-data blocks A0, to A7 are written in the content buffer during the first eight frame periods, and at least frame-data A0 is read, hence at least segment-0 of the buffer becomes available for storing a new frame-data block. During frame period 5000, for example, frame-data block A5000 is written in the buffer segment of index 5000 _(modulo 8); that is segment-0, overwriting frame data block A4992. During frame period 5091, frame-data block A5091 is written in the buffer segment of index 5091 _(modulo 8); that is segment-3, overwriting frame data block A5088.

FIG. 61 illustrates use of circular content buffer 5330 to relate control data received from VR headset to respective frame data. The exemplary circular content buffer is logically divided into 24 segments 6120, indexed as 0 to 23, each segment having a storage capacity sufficient to hold a frame data block comprising frame pixels and relevant metadata. With cyclic frame numbers ranging from 0 to 16383, for example, segments of indices 0 to 23 may contain data relevant to 24 consecutive frames of indices (0, 1, . . . , 22, 23) just before content of frame 24 is written, frames of indices (920, 921, . . . , 942, 943) just before content of frame 944 is written, or (16380, 16381, 16382, 16383, 0, 1, . . . , 19), just before content of a frame of cyclic index 20 is written, for example.

A frame data block 5730 (FIG. 57 ) sent from acquisition module 4720, which is collocated with the view adaptor 5210, to distant VR headset 4750 experiences a propagation delay of Δ₁. The VR headset 4750 sends control message 5740 (FIG. 57 ) to the view adaptor 5210 after a processing delay of δ*. A control message 5740 experiences a propagation delay of Δ₂.

A control message 5740 corresponding to the frame of index 0 is received at the content-filter controller 5320 after frame data of a frame of index 06 is written in the buffer 5330. Frame data of the frame of index 00 is then read (reference 6182) from the buffer and submitted, together with the control message, to the content filter 4760. Frame data of a frame of index 07 is then written (reference 6188) in the buffer 5330.

A control message 5740 corresponding to the frame of index 11 is received at the content-filter controller 5320 after frame data of a frame of index 17 is written in the circular content buffer 5330. Frame data of the frame of index 11 is then read (reference 6192) from the buffer and submitted, together with the control message, to the content filter 4760. Frame data of a frame of index 18 is then written (reference 6198) in the buffer 5330.

Circular-Buffer Content

At the end of a current-frame period, the circular buffer 5330 of the view adaptor 5210 contains content data of a current frame in addition to content data of a number of preceding frames to a total of L frames, L>1. After the initial L frames, the circular buffer retains frame data of the latest L frames. The number L is selected so that the duration of L frame periods exceeds the round-trip transfer delay between the view adaptor 5210 and the VR headset 4750. The transfer delay includes the round-trip propagation delay in addition to any processing delay or queueing delay en route.

As mentioned above, the frame identifier f_(j), j≥0, has values between 0 and (Γ−1) where Γ is a sufficiently large integer, thus, f_(j)=j_(modulo Γ), Γ≥L. The tables below illustrate buffer content for a case where L is only 8 and δ>>L; δ=16384, for example. With the frames indexed sequentially, at the start of frame f₀, the buffer is empty. During f₀, the content of frame 0 is stored in the buffer. At the start of frame f₁, the buffer contains content of f₀. During f₁, the content of frame 1 is stored in the buffer. At the start of frame f₂, the buffer contains contents of f₀ and f₁. During f₂, the content of frame 2 is stored in the buffer. At the start of frame f₇, the buffer contains contents of f₀ to f₆. During f₇, the content of frame 7 is stored in the buffer.

Frame period 0 1 2 3 4 5 6 7 Stored frames — 0 0-1 0-2 0-3 0-4 0-5 0-6

If the actual round-trip transfer delay is 5.5 frame periods, for example, then at the start of frame 7, the content of frame 0 can be read (reference 5332) from the buffer to be presented together with the view-region definition data 5324, corresponding to frame 0, received from the VR headset to content filter 4760 which produces a content-filtered frame (reference 5280).

Starting with frame f₈, the buffer always contains frame data of 8 frames (L=8) as indicated in the tables below. Thus, at the start of frame 8, the buffer contains frame data of frames 0 to 7, at the start of frame 88, the buffer contains frame data of frames 80 to 87, and so on. The buffer contains frame data for a maximum of L frames regardless of the value of Γ.

Frame period 8 9 10 11 12 13 14 15 Stored frames 0-7 1-8 2-9 3-10 4-11 5-12 6-13 7-14

Frame period 88 89 90 91 92 93 94 95 Stored frames 80-87 81-88 82-89 83-90 84-91 85-92 86-93 87-94

FIG. 62 illustrates content 6100 of circular buffer 5330 during successive framed periods 160 to 175, with L=16, indicating for each frame to be written (reference 6130) in the circular buffer previous frames held on the circular buffer (reference 6140). At the start of frame 160, the buffer contains content data of frames 144 to 159. During frame 160, the content of frame 160 overwrites the content of frame 144. Thus, at the end of frame 160, the buffer contains content data of frames 145 to 160, and so on.

Preferably, content data is read from the buffer before overwriting any stored content with content of a new frame. The communication path 5250 from the VR headset to the view adaptor 5210 preferably preserves the sequential order of view-region definitions corresponding to successive frames. However, content-filter controller 5320 may be configured to re-order the view-regions definitions where needed.

FIG. 63 illustrates a method 6300 of generating operator-defined content using the distributed system of FIG. 52 . Process 6310 continually receives a multimedia signal stream 4712 and signal descriptors 4732 from a panoramic signal source 4710. Process 6320 generates a pure multimedia signal stream 4730 according to the signal descriptors 4732. Process 6330, implemented at acquisition module 4720, extracts a current-frame data and inserts a cyclic frame index. Process 6340 transmits the current frame data and corresponding cyclic frame index to the VR headset 4750. Process 6350 places the current frame data in cyclic content buffer 5330 of view adaptor 5210. Process 6360 receives control data 5260, which includes a new gaze position and the index of a respective frame, from the VR headset 4750. Process 6370 presents control data 5260 to content-filter controller 5320 of view adaptor 5210. Process 6380 receives the content-filtered signal 5280 from content filter 4760 of the view adaptor 5210 and transmits the signal to a broadcasting station and/or a streaming server. The content-filtered signal may be compressed prior to transmitting.

FIG. 64 illustrates a method 6400 of adaptive content filtering based on changes of gaze position. To start, content-filter controller 5320 initializes the gaze position (process 6410) as a default value, for example to correspond to a midpoint of frame display. A default view region is defined accordingly. Process 6420 receives a new gaze position and a corresponding frame index from the VR headset 4750. Process 6430 determines an absolute value of the difference between the new gaze position and a current gaze position. If the difference is insignificant, where an absolute value of the difference is below a predefined threshold, as determined in process 6440, the current gaze position remains unchanged, hence the view region remains unchanged, and content-filter controller 5320 reads (process 6470) frame data corresponding to the received frame index 5322 from the circular buffer 5330. Otherwise, if the difference is significant (process 6440), where the absolute value at least equals the threshold value, a view region corresponding to the new gaze position is defined (process 6450) and the current gaze position is set (process 6460) to equal the new position for subsequent use in process 6430. Content-filter controller 5320 then reads frame data corresponding to the received frame index 5322 from the circular buffer 5330.

Content filter 4760 of view adaptor 5210 generates a content-filtered frame 5280 according to the view region and process 6420 is revisited to receive a new gaze position.

Thus, the present invention provides a method of communication comprising employing a virtual-reality headset, 4750, FIG. 47 , to produce a virtual-reality display of a pure signal 4730 comprising multimedia signals and generate geometric data 4752 defining a selected view-region definition data of the display. The virtual-reality display may be produced from the pure signal using an internal display device of the virtual-reality headset 4750 and/or an external display device 4770.

A content filter 4760 extracts a content-filtered signal 4764 from the pure signal according to the geometric data. The content-filtered signal is directed to a broadcasting apparatus. The virtual-reality headset comprises a processor and memory devices to perform the process of generating the geometric data and tracking of changing gaze orientation of an operator 4752 wearing the virtual-reality headset 4750.

A sensor within the virtual-reality headset provides parameters defining a current gaze orientation of the operator 4725. A content filter is devised to determine the selected view region according to the current gaze orientation and a predefined shape of the view region.

The pure signal 4730 is produced from a source signal 4712 received from a panoramic signal source 4710. The source signal 4712 includes multimedia signal components 4943 and a signal descriptor 4732 identifying the multimedia signal. The signal descriptor identifies content of the source signal as one of:

-   -   the pure signal 322 (FIG. 3 );     -   a raw signal 312;     -   a warped compressed signal 342; and     -   a de-warped compressed signal 343.

If the content of the source signal is not the pure signal, the source signal is supplied to a matching pure-signal generator 4950 (FIG. 49 ) to produce the pure signal.

The content-filtered signal 4764 is extracted from the pure signal according to the geometric data. The content-filtered signal 4764 comprises samples of the pure signal corresponding to content within the contour. The function of the content filter 4760 may be performed within the virtual-reality headset so that extracting the content-filtered signal may be performed using processor executable instructions stored in a memory device of the virtual-reality headset. Alternatively, extracting the content-filtered signal may be performed at an independent content filter 4760 coupled to the virtual-reality headset and comprising a respective processor and a memory device.

The content-filtered signal 4764 may be compressed to produce a compressed filtered signal 4864 (FIG. 48 ). The compressed filtered signal may then be transmitted to a broadcasting station, through channel 4880, and/or a Universal Streaming Server, through channel 4890 and network 150.

The source signal 4712 received from the panoramic signal source 4710 may be relayed, using repeater 4810 (FIG. 48 ), to a streaming apparatus 4820 that comprises an acquisition module 4720-B and a Universal Streaming Server 120. The acquisition module generates a replica of the pure signal 4730 which is supplied to the Universal Streaming Server. The Universal Streaming Server is configured to provide viewer content control to a plurality of viewers 180 (FIG. 48 ).

As described above, the present invention provides a communication system configured to receive a modulated carrier source signal 4712 and extract a content-filtered signal 4764 for broadcasting. The system comprises a virtual-reality headset 4750, a content filter 4760, and a transmitter.

The virtual-reality headset is configured to present a virtual-reality display of a pure signal 4730 derived from the received modulated carrier source signal 4712. The content filter is configured to generate a content-filtered signal 4764 from the pure signal according to the geometric data. The transmitter sends the content-filtered signal along a channel to a broadcasting station.

The virtual-reality headset comprises a sensor of gaze orientation of an operator 4752 wearing the virtual-reality headset and a memory device storing processor executable instructions causing a processor to generate geometric data 4752 defining a view region of the display according to the gaze orientation. The content filter comprises a respective processor and a memory device.

The communication system further comprises an acquisition module 4720 (FIG. 47 , FIG. 49 ) for deriving the pure signal 4730 from the received panoramic multimedia signal 4712. The acquisition module comprises a receiver 4942, a set of pure-signal generators 4950 for generation the pure signal, and a selector 4946. Receiver 4942 generates from a modulated carrier source signal a source multimedia signal and a corresponding signal descriptor. Selector 4946 directs the source multimedia signal to a matching pure-signal generator 4950 according to the corresponding signal descriptor.

The virtual-reality headset is further configured to determine a gaze position of the operator 4752 and the geometric data 4752 as representative spatial coordinates of a contour of a predefined form surrounding the gaze position. The content-filtered signal 4764 comprises samples of the pure signal 4730 corresponding to content within the contour.

Optionally, the communication system may comprise a repeater 4810 (FIG. 48 ) for relaying the modulated carrier source signal 4712 sent from a panoramic signal source 4710 to a streaming apparatus 4820. The streaming apparatus comprises an acquisition module 4720 for generating a replica of the pure signal 4730 and a Universal Streaming Server 120 receiving the pure signal 4730 and providing content-filtered signals based on individual viewer selection.

FIG. 65 illustrates a second system for combined selective content broadcasting and streaming employing a panoramic camera and a VR headset, the system comprising a muting facility 6520 and a remote content controller 6540 which comprises an acquisition module 4720 and a distant content selector 5240. The routing facility 6520 communicates with the remote content controller 6540 through a network 6530. FIG. 66 details the muting facility 6520 of FIG. 65 .

As in the configuration of FIG. 51 , the 4π camera produces a broadband signal which may be de-warped and/or compressed in source processing unit 4714 then supplied to transmitter 4716 to produce modulated carrier source signal 4712 sent to routing facility through transmission channel 6522. The muting facility receives the modulated carrier source signal 4712 at input (a) and supplies the signal to a repeater 6610 (FIG. 66 ) which produces:

-   -   an amplified modulated carrier 6551 directed from output (c) to         remote content controller 6540 through a channel 6524, network         6530, and channel 6544 from network 6530 to produce an         operator-defined content filtered signal; and     -   an amplified modulated carrier 6552 directed from output (b) to         a Universal Streaming Server 120 embedded in a cloud computing         network 6570 to produce viewers-defined content-filtered         signals.

Control data is sent from the remote content controller 6540 to the routing facility 6520 through channel 6546, network 6530, and channel 6526. The routing facility 6520 captures the control data at input (d) and a receiver 6670 detects control data from control data 6548 sent from remote content controller 6540 through network 6530 and channel 6526. The detected control data is supplied to view adaptor 5210 which produces an operator-defined content-filtered signal 4764. The content-filtered signal 4764 is compressed in compression module 4862 and supplied to transmitter 4870 to produce a modulated carrier signal to be directed from output (e) through channel 6528 to broadcasting station 6580 and through channel 6529 to one of the Universal Streaming Servers 120 through channel 6529 and network 6530.

FIG. 67 details the remote content controller 6540 which comprises an acquisition module 4720 (FIG. 47 ) and distant content selector 5240 which includes a virtual-reality headset 4750 used by operator 4725. A frame-number extraction module 6710 extracts a cyclical frame number from a pure multimedia signal 4730 detected at the acquisition module 4720. A frame-number insertion module 6712 inserts the extracted cyclical frame number into control data 6548 which define the operator's preferred view region of the display. A refresh module 6720 collocated with distant content selector 5240 further modifies the control data 6548.

Alternatively, the process of relating control data (individual control messages) 6548 to video frames identified at module 4715 (FIG. 47 , FIG. 65 ) may rely on using “time-stamps” and measuring the round-trip transfer delay between the view adaptor 5210 (FIG. 52 , FIG. 66 ) and the distant content selector 5240 (FIG. 52 , FIG. 67 ). However, the use of cyclical frame numbers as described above is preferable.

Hybrid System for Selective Content Broadcasting

FIG. 68 illustrates a hybrid system for selective content broadcasting of multimedia signals using a panoramic camera, a bank of content filters, and a conventional switcher (selector). The multimedia signals are generated at signal source 4710 which comprises a 4π camera 310 coupled to a source-processing unit 4714 and a broadband transmitter 4716. The camera captures a panoramic view and produces a raw signal 312 which may be directly fed to broadband transmitter 4716 or supplied to source-processing unit 4714 which processes the raw signal 312 to produce a corrected (de-warped) signal 322, a compressed raw signal 342, or a compact signal (de-warped and compressed) 343 as illustrated in FIG. 3 in addition to inserting other control data. The output of the source-processing unit 4714 is supplied to broadband transmitter 4716.

The broadband transmitter 4716 sends a modulated carrier source signal 4712 through the transmission medium 4718 to an acquisition module 4720 which is a hardware entity comprising a receiver 4940 (detailed in FIG. 49 ), a processor, and memory devices storing processor-readable instructions which cause the processor to perform functions of de-warping and/or decompression as illustrated in FIG. 49 . The acquisition module produces a pure multimedia signal 4730 which is fed to a bank 6825 of content filters 6832 configured to provide filtered signals collectively covering the entire view captured by the panoramic camera 310. Four content filters 6832 individually labelled “A”, “B”, “C”, and “D”, are illustrated. The output signal 6840 of each content filter 6832 is fed to a respective display device 4650. The display devices coupled to the four content filters, labelled “A” to “D”, are individually identified as 4650-A, 4650-B, 4650-C, and 4650-D, respectively.

A manually operated view-selection unit 4660, similar to that of FIG. 46 , selects one of baseband signals fed to the display devices 4650. An operator 4662 observes all displays and uses a selector (also called a “switcher”) 4664 to direct a preferred output signal to a transmitter 4680 (FIG. 46 , FIG. 68 ). The transmitter 4680 is coupled to a transmission medium through an antenna or a cable 4690.

Mirroring Versus Editing

A VR headset may be configured to generate, and transmit, a view-field video signal representing a view field of what a person wearing a VR headset views. Thus, whatever a user wearing the VR headset views can be displayed in another device such as a mobile phone or a television set. The view-field signal may be broadcast or streamed through a network.

The system of FIGS. 65-67 enables selecting view-regions of interest within the view-field of a VR headset, which may vary significantly for different VR-headset types. A user of a VR headset selects an image portion of each image surrounding a time-varying gaze position. The system does not fan out a video signal corresponding to the field of view of the VR headset. Rather, the system edits the content of each video frame where a view region is delineated according to a predefined contour surrounding a gaze position. The VR headset receives a panoramic video signal from a panoramic multimedia source which uses a wide-angle camera covering a solid angle of up to 4π Steradians. Only a small portion of the panoramic video signal may be of interest to a viewer. The user of the VR headset views an entire panoramic view and selects a portion to be broadcast or to be provided to a streaming server.

The view adaptor of FIG. 66 does not generate a replica of what a person wearing the headset views. The view adaptor extracts, from a panoramic video signal, a content-filtered signal corresponding to a time-varying selection of a view region.

FIG. 69 depicts a method 6900 of selective content broadcasting implemented in the system of FIG. 51 . A panoramic signal source including a stationary 4π camera 310, source-processing unit 4714, and a broadband transmitter 4716 is appropriately positioned in the field of events to be covered. A pure multimedia signal 4730 is acquired (process 6910, acquisition module 4720) at a location close to the panoramic signal source through a transmission medium 4718 which can be a broadband wireless channel or a fiber-optic link. The panoramic signal is displayed (process 6920, internal display of a VR headset and/or display device 4770). An operator 4725 inspects the display using a VR headset 4750 (process 6930). A content-filtered signal corresponding to the operator's gaze direction is acquired from said VR head set. The content-filtered signal is compressed (process 6940, compression module 4862) to produce a compressed signal which is transmitted to a broadcasting station (process 6950, transmitter 4870).

FIG. 70 depicts a method 7000 of selective content broadcasting implemented in the system of FIG. 68 . As in the method of FIG. 69 , a panoramic signal source including a 4π camera 310, a source processing unit 4714, and a broadband transmitter 4716 is appropriately positioned in the field of events to be covered. A pure multimedia signal 4730 is acquired (process 7010, acquisition module 4720) at a location close the panoramic signal source through a transmission medium 4718.

A bank 6825 of content filters 6832 is provided and the pure multimedia signal 4730 is supplied to each content filter 6832. Each content filters 6832 is configured to extract (process 7020) from the panoramic signal a respective filtered signal corresponding to a respective viewing angle. Collectively, the filtered signals cover the entire field of events. Naturally, the viewed portions of the field corresponding to the filtered signals are bound to overlap. The filtered signals are displayed (process 7030) on separate display devices. An operator 4662 (FIG. 68 ) activates a selector (switcher) 4664 to direct a preferred filtered signal to a transmitter 4680 (process 7040). The modulated carrier at output of the transmitter is sent to a broadcasting station (process 7050).

FIG. 71 is a flowchart depicting basic processes of the system of FIG. 48 and FIG. 51 . In process 7110, a modulated carrier source signal 4712 is received at a monitoring facility 5120. In process 7130, source signal 4712 may be relayed (repeater 4810) to a streaming subsystem 4808. In process 7112, an acquisition module 4720 acquires a pure multimedia signal 4730 from source signal 4712. In process 7114, a content selector 4740 generates an operator-defined content-filtered multimedia signal intended for broadcasting. The signal may be compressed before transmitting to a broadcasting facility as well as to Universal Streaming Server 120 to be used for a default viewing selection (process 7120).

At the streaming subsystem 4808, an acquisition module 4720 acquires a replica of pure multimedia signal 4730 which is supplied to the Universal Streaming Server 120 (process 7140). The Universal Streaming Server sends a full content signal, preferably at a reduced flow rate as illustrated in FIGS. 13, 14, and 15 , to client devices 180 communicatively coupled to the Universal Streaming Server 120 (process 7142). The Universal Streaming Server 120 may receive a viewing preference from a client 180 (process 7144) and produce a respective content-filtered signal (process 7146). In the absence of a client's preference indication, content based on the default viewing selection may be sent to the client. The Universal Streaming Server 120 retains content based on viewers' selections as illustrated in FIG. 32 in addition to the default viewing selection (process 7148).

FIG. 72 illustrates a method of content-filtering of a panoramic multimedia signal to produce an operator-defined content for broadcasting. The method comprises receiving (process 7220) a source signal 4712 from a panoramic signal source 4710, generating (process 7230) at an acquisition module 4720 (FIG. 47 , FIG. 51 ) a pure signal 4730 (FIG. 47 ) from a multimedia signal 4712, (FIGS. 47, 48, 49, 51 ) received from a panoramic multimedia source 4710 (FIG. 47 , FIG. 51 ) and employing a content selector 4740 configured to extract from the pure signal content-filtered signals corresponding to varying view-regions of a displayed pure signal.

The content selector 4740 performs processes of employing a virtual-reality headset 4750 (FIG. 47 , FIG. 50 ) to view a display (process 7240, FIG. 72 ) of the pure signal 4730 and determine a current gaze position (process 7244) from the virtual-reality headset.

A reference gaze position is initialized (process 7242, FIG. 72 ) as a default value; corresponding to a frame center, for example). The VR-headset continually senses gaze positions of an operator wearing the headset.

A displacement 5530 (FIG. 55 ) of the current gaze position from a reference gaze position is then determined (process 7246). The reference gaze position is updated to equal the current gaze position subject to a determination that the displacement 5530 exceeds a predefined threshold (processes 7248 and 7250, FIG. 72 ).

View-region definition data are then generated (process 7260) using the reference gaze position and a predefined contour shape (such as a rectangle). A content-filtered signal 5280 (FIG. 52 ) is extracted from the pure signal 4730 (process 7270) according to the view-region definition data and transmitted to a broadcasting facility (process 7274). The content-filtered signal 4764 may be compressed (process 7272) before transmission.

The gaze position is represented as a set of parameters or a vector of multiple dimensions. Different measures of gaze-position displacement may be used. According to one measure, a first vector (a first set of parameters) representing the reference gaze position and a second vector (a second set of parameters) representing a current gaze position are compared. The displacement is then determined as a sum of absolute values of shifts of coordinate values defining the gaze position as illustrated in FIG. 55 .

A set of parameters defining a gaze position may be selected as the conventional “pan, tilt, and zoom” (PTZ) parameters acquired from a sensor of the virtual-reality headset. The view-region definition data generated in process 7260 may be retained for reuse for cases where the displacement is less than or equal to the predefined threshold (processes 7248, 7270).

FIG. 73 and FIG. 74 illustrate a method of content-filtering of a panoramic multimedia signal implemented in the system of FIG. 65 where a routing facility 6520, which may be mobile, is located in the vicinity of the panoramic signal source 4710 and communicates with a remote content controller 6540 which houses a distant content selector 5240 with an operator 4725 wearing a virtual-reality headset 4750.

FIG. 73 illustrates processes performed at the remote content controller 6540. A source signal (a modulated carrier signal) 4712 is received at distant content selector 5240 (process 7310). A reference gaze position is initialized as a default position (process 7320) which may be a position selected so that a first observed gaze position would force computation of a view-region definition. A pure multimedia signal 4730 is acquired from the source signal 4712 at distant content selector 5240 (process 7330).

The acquired pure multimedia signal at distant content selector 5240 is displayed (process 7340). A Refresh module 6720 collocated with distant content selector 5240 (FIG. 67 ) performs processes 7350 affecting the rate of updating view regions. A frame-index extraction module 6710 extracts (process 7352) a cyclic frame identifier from a pure multimedia signal detected at the acquisition module 4720 of the remote content controller 6540 (FIG. 67 ). A frame-index insertion module 6712 inserts frame numbers into control data 5260 directed to the view adaptor 5210. A preferred frame identifier is a cyclic frame index which is the preferred identifier considered herein. A current gaze position 5520 (FIG. 55 ) is determined from an output of a virtual-reality headset of the distant content selector 5240 (process 7354).

Process 7356 determines a displacement of the current gaze position from the reference gaze position. Process 7358 determines whether the displacement exceeds a predefined displacement threshold Δ*. If so, the current gaze position becomes the reference gaze position (process 7370) and a control message containing the new reference gaze position together with the corresponding frame identifier is formed (process 7372). Otherwise, if the displacement is insignificant, being less than or equal to Δ*, process 7374 generates a message containing the corresponding frame identifier and a null gaze position indicating that a frame data block stored in the circular content buffer 5330 may be displayed according to a previous view-region definition. The control message formed in process 7372 or process 7374 is transmitted (process 7378) to view adaptor 5210. Due to tracking latency of the virtual-reality headset, a (minor) shift of the cyclic frame number may be needed.

Process 7380 receives a new message from remote content controller 6540. Process 7352 is then revisited.

FIG. 74 illustrates processes 7400 performed at view adaptor 5210 residing in the routing facility 6520.

Process 7410 receives from refresh module 6720 of the remote content controller 6540 a new gaze position 5520 and a corresponding cyclic frame number 5510 (FIG. 55 ). Process 7410 simultaneously directs the cyclic frame identifier 7412 to process 7420 and the new gaze position to process 7440.

Process 7420 determines the address of a frame data block 5332 in content buffer 5330 according to the received cyclic frame number 7412. The frame data block 5332 is read from the content buffer (process 7430) and directed to process 7460 to generate a content-filtered signal based on the last view-region definition.

Process 7440 directs the new gaze position to process 7460 if the new gaze position is a null position. Otherwise, process 7450 is activated to generate and retain a new view-region definition which would overwrite a current view-region definition. The new view-region definition would be based on the new gaze position and a predefined region shape (contour).

Process 7460 generates a content-filtered signal 5280 based on the latest view-region definition which would be the one generated in process 7450 or a previous view-region definition when a control message includes a null gaze position indicating no change or an insignificant change of the gaze position.

The content-filtered signal may be compressed (process 7462) at muting facility 6520 (FIG. 66 ) supporting the view adaptor 5210. The compressed content-filtered signal is transmitted from the routing facility (process 7464). New content-selection data (new gaze position and frame identifier) is received from refresh module 6720 (process 7480) and the above processes of generating content-filtered signals are continually executed, starting with process 7410.

The above processes of generating content-filtered signals may be activated each frame period or each period of a predefined number of frames (for example, each 8-frame period).

It is noted that content filter 4760 (FIGS. 47, 50 and 53 ), as well as the content filters 6832 (FIG. 68 ) employ hardware processors and memory devices storing processor-executable instructions which cause the hardware processors to implement respective processes of the present invention.

Geographically Distributed System

The panoramic multimedia source simultaneously transmits a panoramic video signal to the content controller having the VR headset and the view adaptor. The content controller receives the panoramic video signal, produces gaze positions of an operator wearing the headset, and communicates the gaze positions and corresponding video-frame indices to the view adaptor. The latency of the content controller (FIG. 67 ) is insignificant. However, the delays T1, and (T2, +T3), indicated in FIG. 75 , may differ significantly, particularly if the paths are established through a shared network.

FIG. 75 illustrates a geographically distributed system of selective video-content dissemination comprising panoramic signal source 4710, distant content selector 5240, and view adaptor 5210. Acquisition modules 4720A and 4720B are collocated with view adaptor 5210 and content selector 5240, respectively. The signal transfer delay 7512 along a path 7510 from the panoramic signal source 4710 to an acquisition module 4720A collocated with the view adaptor 5210 is denoted T₁. The signal transfer delay 7522 along a path 7520 from the panoramic signal source 4710 to an acquisition module 4720B collocated with distant content selector 5240 is denoted T₂. The signal transfer delay 7532 along a path 7530 from the distant content selector 5240 to the view adaptor 5210 is denoted T₃. Any of paths 7510, 7520, and 7530 may be dedicated communication paths or a path established through a network. If a path is established through a network, the transfer delay includes any queuing delay within the network.

The panoramic signal source 4710 sends a video signal to acquisition module 4720A coupled to the view adaptor 5210 but may send either the video signal or a frame-sampled signal derived from the video signal to acquisition module 4720B coupled to the VR headset 4750. The frame-sampled signal comprises selected video frames, for example one of each 16 successive frames of the video signal. A frame selector 7550 coupled to the panoramic signal source produces the frame-sampled signal according to prescribed sampling parameters.

Each identified gaze position is associated with a respective video-frame index. It may be sufficient to capture the time-varying gaze position at spaced time instants (every 0.2 seconds, for example) instead of every video-frame period.

Referring to FIG. 52 and FIG. 75 , the view adaptor receives:

-   -   video-frame data from a panoramic multimedia source 4710 along a         first path 7510; and     -   control data from the VR headset of the distant content selector         5240 along a second path 7530.

The view adaptor is configured to handle the discrepancy of arrival times of video-frame data and corresponding control data to produce a content filtered signal.

FIG. 76 illustrates differences of arrival times of frame content data and corresponding control data at the video adaptor. Frame indices corresponding to frame data received at view adaptor 5210 from the panoramic signal source 4710 are denoted f₀, f₁, f₂ . . . etc. Frame indices corresponding to control data received at view adaptor 5210 from the VR headset are denoted ϕ₀, ϕ₁, ϕ₂, . . . etc.

As illustrated, for a case where T₁ is less than (T₂+T₃), content data of a specific frame received from source (reference 7620) arrives before control data of the specific frame (reference 7640). For example, control data of the frame of index 0 arrives after approximately 4.5 frame periods following receiving the content of the frame.

For a case where T₁ is larger than (T₂+T₃), content data of a specific frame received from source (reference 7660) arrives after control data of the specific frame (reference 7680). For example, control data of the frame of index 0 arrives after approximately 5.2 frame periods before receiving the content of the frame. A communication path between two points, whether dedicated or established through a network, is not necessarily routed along a line-of-sight. Thus, T₁ is not necessarily less than (T₂+T₃). Additionally, when the paths are established through a shared network, the transfer delays depend heavily on network traffic conditions.

Editing Video Frames

The process of editing individual video frames is performed at a view adaptor which receives the panoramic video signal directly from the panoramic multimedia source and receives the gaze positions and corresponding vide-frame indices from the content controller comprising the VR headset. The panoramic multimedia source, the content controller, and the view adaptor are generally geographically distributed as illustrated in FIG. 75 (detailed in FIGS. 65, 66, and 67 ). The transfer delay along network paths 7510, 7520, and 7530 may be time varying due to changes in network conditions.

Matching gaze positions with respective video frames to extract a video-frame portion according a predefined contour is enabled with the use of a circular content-buffer and a circular control-buffer properly provisioned to hold sufficient data to account for the differing delays along a path from the panoramic multimedia source to the view adaptor, and along a path from the panoramic multimedia source to the VR headset then a path from the VR headset to the view adaptor as illustrated in FIG. 76 , reproduced below.

The view adaptor presents video-frame data and corresponding control data to content filter 4760 (FIG. 78 ) to produce a content filtered signal. To handle the discrepancy of arrival times, at the view adaptor, of the video-frame data and corresponding control data, a circular content-buffer and a circular-control buffer are sized and organized so that content data of each received video-frame and corresponding control data (including view-region definition) are present in the circular content-buffer and the circular control-buffer, respectively, as illustrated in FIG. 81 .

FIG. 77 illustrates the effect of signal-transfer delay jitter on relative arrival times of frame content data and corresponding control data at the video adaptor 5210. Frame indices corresponding to frame content data (reference 7730) are denoted f₄, f₅, etc. Frame indices corresponding to frame control data (reference 7740) are denoted ϕ₄, ϕ₅, etc.

In a case where T₁ is less than (T₂+T₃), which is the most likely scenario, and under the condition of no delay jitter (reference 7710), the control data corresponding to a frame arrives at the view adaptor 5210 after the content of the frame arrives. In which case, it suffices to use the circular content-buffer 7750 (similar to circular content-buffer 5330). However, with even a moderate level of delay jitter (reference 7720), the succession of arrival times at the view adaptor 5210 of frame-specific control data and content data may not be consistent. For example, while control data corresponding to a frame of index 5 arrives after receiving the content data of the frame, control data corresponding to the frame of index 6 arrives before receiving the content data of the frame. To enable matching same-frame control data and frame content, a circular control-buffer 7760 in addition to the circular-content buffer is provided. The circular control buffer is operated in a manner similar to that of the circular content buffer. The circular content-buffer holds content data 7752 of a number of frames of a moving window of frames. The frames are assigned cyclical frame indices 7751 as described above. Content data of a frame of cyclical index j is stored in a buffer division of index j, 0≤j<L, L being a predefined cyclical period as described above. The circular control-buffer holds control data 7762 of a number of frames of a moving window of frames. The frames are assigned cyclical frame indices 7761 and control data of a frame of cyclical index j is stored in a buffer division of index j.

FIG. 77 illustrates the use of a dual circular buffer comprising a circular content-buffer and a circular control-buffer for the case where the virtual-reality headset receives the full video signal and communicates control data every video-frame period.

FIG. 78 illustrates a view adaptor 5210B comprising a circular content-buffer 5330, a circular control-buffer 7760, content filter 4760, a content-filter controller 7820. As described above, content-filter controller 5320 (FIG. 53 ) receives control data comprising a view-region definition and a respective frame index from the distant VR headset then reads frame data of the respective frame index from the circular content-buffer 5330.

Content-filter controller 7820 receives control data comprising a view-region definition and a respective frame index from the distant VR headset then inserts the respective frame index in the circular control-buffer 7760. An index 7822 of a frame data block 5332 to be read from the circular-content buffer is determined according to stored frame indices in the circular-control buffer and stored frame indices in the circular content-buffer 5330.

FIG. 79 illustrates data-storage organization 7900 in the circular content-buffer 7750 and the circular control buffer 7760 for the case where the virtual-reality headset communicates control data every video-frame period. The circular content-buffer is organized into L divisions 7910 each division storing content data 7920 of a video frame. Content of a frame of cyclical index j is stored in a division of the same index j, 0≤j<L. Likewise, the circular control-buffer is organized into L divisions 7930 each division storing control data (gaze positions) 7940 of a video frame. Control data of a frame of cyclical index j is stored in a division of the same index j. As indicated, the buffers' contents are cyclically overwritten (reference 7950).

FIG. 80 illustrates data-storage organization 8000 in a circular content-buffer and a circular control buffer for the case where the virtual-reality headset communicates control data every Y video-frame periods, Y>1. The circular content-buffer is organized into L divisions 7910 each division storing content data 7920 of a video frame. Content of a frame of cyclical index j is stored in a division of the same index j, 0≤j<L. The circular control-buffer is organized into ┌L/Y┐ divisions 8030 each division storing control data (gaze positions) 8040 received from the VR headset every Y video-frame periods. Thus, control data of a frame of cyclical index j is stored in a division of the index ┌j/Y┐. The divisions of the circular control-buffer are denoted γ₀, γ₁, γ₂, and γ₃. As indicated, the buffers' contents are cyclically overwritten (8051, 8052).

FIG. 81 illustrates data-storage organization 8100 in a dual circular buffer comprising a circular content buffer configured to hold contents 8122 of 32 video frames (L=32) of cyclical indices f₀ to f₃₁, and a circular control-buffer holding control data 8132 received every four video frame periods (Y=4). Thus, the circular control-buffer is organized into eight divisions (┌L/Y┐, L=32, Y=4). The indices 8130 of storage divisions of the circular control-buffer are denoted γ₀ to γ₇. The indices 8120 of storage divisions of the circular content-buffer correspond to cyclical indices of the video frames.

It is noted that: ┌R┐ denotes the value of R if R is an integer or the nearest higher positive integer to R if R is a positive real number, and └R┘ denotes the value of R if R is an integer or the integer part of R if R is a positive real number.

Thus, the invention provides a device 4740 for selective video-content dissemination. An acquisition module 4720 receives a modulated carrier 4712 from a panoramic multimedia source 4710 and extracts a pure video signal 4730. A virtual-reality headset 4750, communicatively coupled to the acquisition module 4720, provides a virtual-reality display of the pure video signal and coordinates of gaze positions of an operator 4725 wearing the virtual-reality headset. Video-frame indices corresponding to the gaze positions are determined.

A content filter 4760, communicatively coupled to the acquisition module 4720 and the virtual-reality headset 4750, employs a hardware processor configured to produce a content-filtered signal 4764 from the pure video signal 4730. The content filter 4760 receives the pure video signal 4730, the coordinates of gaze positions, and the corresponding video-frame indices. Geometric data that define a view region of the display corresponding to each gaze position are then generated. A content-filtered signal extracted from each frame of the pure video signal according to respective geometric data is then transmitted to a communication facility for dissemination.

The communication facility may be a broadcasting station or a streaming server 120 (FIG. 48 ) configured to enable viewer content selection and provide the content-filtered signal based on the operator's gaze position as a default selection for the case where a streaming server viewer does not select a view region.

The acquisition module 4720, FIG. 49 , comprises a receiver 4940 configured to detect from the modulated carrier 4712 a source multimedia signal and a corresponding signal descriptor. A signal descriptor indicates processes performed at the signal source (FIG. 3 ). The acquisition module employs a set of pure-video-signal generators 4950, each tailored to a respective signal descriptor, to generate the pure video signal according to a descriptor of the source multimedia signal. A selector 4947 directs the source multimedia signal to a matching pure-video-signal generator according to the corresponding signal descriptor for generating the pure video signal.

The content-filtered signal comprises samples of the pure video signal corresponding to points within the view region. Optionally, the virtual-reality headset provides an indication of a view-region shape of a predefined set of view-region shapes. The content filter then generates the geometric data according to a respective view-region shape.

The invention further provides a geographically distributed system 5200 for selective video-content dissemination. The system comprises a content selector 5240 and a view adaptor 5210. The content selector 5240 includes a virtual-reality headset 4750.

The virtual-reality headset 4750 receives from a source a specific signal which may be either a source video signal or a frame-sampled signal (FIG. 75 , frame selector 7550) derived from the source video signal. The virtual-reality headset 4750 displays the specific signal and determines gaze positions, at spaced time instants, of an operator wearing the headset. The gaze positions, together with corresponding video-frame indices, are communicated for subsequent processing.

The view adaptor 5210 employs a hardware processor 5450 (FIG. 54 ) configured to receive the source video signal from the source and receive the gaze positions and corresponding frame indices from the virtual-reality headset. To counter the effect of varying signal transfer delays, the view adaptor 5210 employs a dual circular buffer comprising a circular content-buffer (6200, FIG. 62, 7750 , FIG. 77 ) for storing full-content frame data derived from the video signal and a circular control-buffer 7760 for storing gaze-positions received from the virtual-reality headset. A content-filter controller 5320 (FIG. 53 , FIG. 54 ) of the view adaptor 5210 determines for each gaze position a surrounding view region according to a predefined view-region shape.

A content filter 4760 (FIG. 53 , FIG. 54 ) extracts a portion of each full-content frame data read from the circular content-buffer according to a view region of a respective gaze position read from the circular control-buffer for dissemination.

The content-filter controller 5320 initializes a reference gaze position, determines a displacement of a current gaze position from the reference gaze position, and updates the reference gaze position to equal the current gaze position subject to a determination that the displacement exceeds a predefined threshold. If the displacement is less than, or equal to, the predefined threshold the current gaze position is set to equal the reference gaze position.

The circular content buffer 6200, 7750 holds full-content of at least a predetermined number of frames. The predetermined number being selected so that the predetermined number times a frame period exceeds a magnitude (i.e., absolute value) of a difference of transfer delay along two paths. The signal transfer delay along one path (7520, 7530) is a sum of signal transfer delay T₂ from the source to the virtual-reality headset and signal transfer delay T₃ from the virtual-reality headset to the content-filter controller. The signal transfer delay T₁ along the other path (7510) is the delay from source to the view adaptor 5210.

The spaced time instants correspond to distant video frames where indices of immediately consecutive video frames differ by a predetermined integer Y, Y>1. The circular control-buffer holds a number of gaze-positions at least equal to ┌H/Y┐, H being the predetermined number of frames for which content data is held in the circular content-buffer. Naturally, H>Y. In the arrangement of FIG. 80 , H=16, Y=4. In the arrangement of FIG. 81 , H=32, Y=4. H equals the predefined cyclical period L.

The content-filter controller 5320 stores a frame content in the circular-content buffer placing frame content of a video frame of cyclical index f*, 0≤f*<L, in a storage division of index f* of the circular content buffer. The content-filter controller stores a gaze position corresponding to a cyclical index ϕ*, 0≤ϕ*<L, in a storage division of index ┌ϕ*/Y┐, L being the predefined cyclical period.

The frame-sampled signal is preferably produced at a frame-selection module (frame selector 7550, FIG. 75 ) coupled to the source. The frame-sampled signal comprises distant video frames where immediately consecutive video frames are separated by a time interval exceeding a duration of a single frame period.

The virtual-reality headset 4750 is configured to define each gaze position as the conventional Pan, Tilt, and Zoom coordinates. The filter controller 5320 further evaluates a gaze-position displacement as a sum of absolute differences of pan, tilt, and zoom values of a first set of coordinates representing the reference gaze position and a second set of coordinates representing the current gaze position.

The virtual-reality headset 4750 is further configured to enable the operator 4725 to select the predefined view-region shape as a default view-region shape or a view-region shape of a set of predefined view-region shapes.

A method of selective video-content dissemination is illustrated in FIGS. 72 to 74 . The method comprises employing a virtual-reality headset to view a display of a video signal, sense gaze positions, at spaced time instants, of an operator wearing the headset, and communicate the gaze positions and corresponding video-frame indices for further processing.

The method employs a hardware processor to initialize a reference gaze position and a corresponding view-region definition then continually perform processes of receiving the video signal, receiving the gaze positions and corresponding video-frame indices, updating the reference gaze position, and generating view-region definition data according to the reference gaze position, extracting a content-filtered signal from the video signal according to the view-region definition data, and transmitting the content-filtered signal to a broadcasting facility.

Updating the reference gaze position is based on determining a displacement of a current gaze position from the reference gaze position. Subject to a determination that the displacement exceeds a predefined threshold 7358, the reference gaze position is set to equal the current gaze position (process 7370) and view-region definition data are generated according to the reference gaze position and a predefined contour shape (FIG. 80 , FIG. 81 ).

Extracting the content-filtered signal comprises processes of determining for each video frame present in the circular content-buffer a respective gaze position present in the circular control buffer and deriving a content-filtered frame from respective full-content frame data (FIG. 81 ).

Determining a displacement of a current gaze position from the reference gaze position (FIG. 55 ) comprises processes of representing each gaze position of the succession of gaze positions as a set of coordinates and evaluating the displacement as a sum of absolute differences of corresponding coordinate values of a first set of coordinates representing the reference gaze position and a second set of coordinates representing the current gaze position.

The virtual-reality headset may receive the entire video signal or receive only a frame-sampled signal of the video signal. The frame-sampled signal is produced at a frame-selection module coupled to a source of the video signal and comprises distant video frames with immediately consecutive video frames separated by a time interval exceeding a duration of a single frame period.

If the virtual-reality head set receives the entire video signal, the display covers all video frames of the video signal. If the virtual-reality head set receives the frame sampled signal, the display covers the distant video frames.

FIG. 82 illustrates a centralized content-filtering apparatus 8200 comprising an acquisition module 4720, an enhanced content filter 8210, a high-capacity view adaptor 8220, and an output unit 8280 including a signal compression module and a transmitter. The acquisition module, enhanced content controller, high-capacity view adaptor, and output unit 8280 are collocated (reference 8250). The centralized content-filtering apparatus is communicatively coupled to at least one panoramic signal source 4710.

The acquisition module 4720 receives a modulated carrier 4712 (FIG. 47 ) from a panoramic signal source 4710, through a path 8204 which may be a direct path or a path through a network 8202, and generates a pure multimedia signal 4730 as well as a respective signal descriptor. The pure multimedia signal 4730 is supplied concurrently (4730A, 4730B) to the enhanced content controller 8210 and the high-capacity view adaptor 8220 through channels 8260A and 8260B, respectively. The enhanced content controller 8210 generates pivotal view positions based on visual fixation of a human operator viewing a display of the pure multimedia signal. The high-capacity view adaptor 8220 defines a view boundary (a view window) around each pivotal view point and extracts corresponding pixels from the pure video signal 4730B. The high-capacity view adaptor 8220 employs multiple content-filtering units operating concurrently as illustrated in FIG. 102 .

FIG. 83 illustrates a spatially distributed content-filtering system 8300 comprising a first acquisition module 4720A coupled to an enhanced content filter 8210, a second acquisition module 4720B coupled to high-capacity view adaptor 8220, and an output unit 8280 coupled to the high-capacity view adaptor 8220. The first acquisition module 4720A is collocated with the enhanced content controller 8210. The second acquisition module 4720B, the high-capacity view adaptor, and the output unit 8280 are collocated. The first acquisition module 4720A and the second acquisition module 4720B are communicatively coupled to at least one panoramic signal source 4710.

Acquisition module 4720A receives a modulated carrier 4712A (FIG. 47 ) from a panoramic signal source 4710, through a path 8304A which may be a direct path or a path through a network 8350A. Acquisition module 4720B receives a replica 4712B of modulated carrier 4712A from the panoramic signal source 4710, through a path 83040B which may be a direct path or a path through a network 8350B. The enhanced content controller 8210 sends pivotal view positions to the high-capacity view adaptor through a path 8340 which may be a direct path or a switched path through a network 8350C. Networks 8350A, 8350B, and 8350C may be a common network such as the Internet.

Acquisition module 4720A generates a pure multimedia signal 4730C as well as a respective signal descriptor. The pure multimedia signal 4730C is supplied to the enhanced content controller 8210 through channels 8360A. Acquisition module 4720B generates a pure multimedia signal 4730D as well as a respective signal descriptor which would be identical to, but not necessarily concurrent with, pure multimedia signal 4730C and corresponding signal descriptor. The pure multimedia signal 4730D is supplied to the high-capacity view adaptor through channels 8360B.

The enhanced content controller 8210 generates pivotal points based on visual fixation of a human operator viewing a display of the pure multimedia signal. The high-capacity view adaptor 8220 defines a view boundary (a view window) around each pivotal point and extracts corresponding pixels from the pure video signal. The view adaptor 8220 employs multiple content-filtering units operating concurrently (FIG. 102 ).

FIG. 84 illustrates a method 8400 of content selection of a multimedia signal based on visual fixation. The method is implemented at the enhanced content controller 8210.

Process 8410 receives a source signal (a modulated carrier signal) 4712 at enhanced content controller 8210. Process 8420 derives a pure multimedia signal 4730 from the source signal 4712. Process 8430 produces a display of the pure multimedia signal. Process 8440 initializes a reference gaze position as a predetermined default position (such as the centre of a display area), setting a visual-fixation count, κ, to equal zero (reference 8448).

Process 8450 detects a gaze of an operator viewing the display. Process 8452 determines a cyclic frame number corresponding to a detected gaze position. Process 8454 retains the detected gaze position as a current gaze position. Process 8456 computes a displacement Δ of the current gaze position from the reference gaze position.

Process 8458 selects either process 8461 or process 8462 as a succeeding process according to the value of gaze-position displacement where process 8461 updates the reference gaze position to be the current gaze position while process 8462 increases the visual-fixation count (κ←(κ+1)). Process 8463 sets the visual-fixation count to equal 1 (κ←1). Process 8465 revisits process 8450 of capturing a new gaze position if the visual-fixation count κ is less than a predetermined threshold κ_(min), or proceeds to process 8472 otherwise. Process 8472 forms a control message containing a frame identifier and a reference gaze position. Process 8478 transmits the control message to the high-capacity view adaptor 8220 then revisits process 8450.

Gaze-Point Sampling Versus Frame Sampling

The term “Gaze-point sampling” refers to a rate of capturing gaze positions. For a typical human, the latency of a significant change of a gaze position exceeds a typical video-frame period. Thus, it is sufficient to detect the gaze position every integer multiple of video-frame periods. An operator wearing a VR headset may, when not blinking, continuously gazes at different points of a display. Capturing a time-varying gaze position during every video-frame period may be unnecessary since a gaze position of a human does not change significantly during a frame period. Thus, the gaze position is preferably captured at spaced time instants; eight frame-periods apart, for example.

The term “Frame sampling” refers to selecting spaced video frames for determining view-regions of interest. Instead of sending all the video frames to the content controller (FIG. 67 ) which includes the VR headset, a frame-sampled video signal may suffice. A frame-sampled signal, comprises distant video frames, e.g., one of each 100 consecutive video frames, which would be sufficient for an operator of the VR headset to select a preferred spatial view region and send corresponding identifying data (control data) to the view adaptor (FIG. 75 , FIG. 78 ) which may be collocated with a broadcasting station distant from the content controller.

Gaze-Point Selection Taking into Account Visual Fixation

FIG. 85 illustrates an example 8500 of selection of pivotal gaze-points selection, based on the method of FIG. 84 with a visual-fixation threshold κ_(min)=4, for a case of sparse clusters of adjacent gaze positions. Two-dimensional gaze positions indicated in a view field 8510 are captured at time instants t₁, . . . , t₁₉. A reference gaze position 8520 is initialed to be the center of a display area, for example, corresponding to an arbitrary time instant to. The gaze positions are preferably captured at regular intervals, every eight frame periods, for example. A cluster of close gaze positions having less than a predetermined number, κ_(min), of gaze positions may be skipped. The visual-fixation threshold, κ_(min), is selected to equal 4 in the illustrated example.

If the operator has a visual fixation to some target point of eight seconds, for example, then—at a frame rate of 30 frames/second—and with gaze positions captured every eight video frames, a corresponding cluster of gaze positions would contain 30 gaze positions for which a single view region is used.

At time instant t₁, process 8458 determines that the displacement Δ_(0,1) of a gaze position from the reference gaze position exceeds a predefined threshold Δ*. Thus, the gaze position at time instant t₁, rather than the gaze position at time instant t₀, becomes the reference gaze position (process 8461) and the visual-fixation count κ is set to 1 (process 8463).

At time instant t₂, process 8458 determines that the displacement Δ_(1,2) of a gaze position from the updated reference gaze position is less than or equal to Δ*. Thus, the gaze position at time instant t₁ continues to be the reference gaze position and the visual-fixation count κ is increased to 2 (process 8462). Since κ<κ_(min), no action is taken and the refresh module continues from process 8465 to processes 8450, 8452, 8454, and 8456.

At time instant t₃, process 8458 determines that displacement Δ_(1,3) of a gaze position from the reference gaze position (still being the gaze position at time instant t₁) is ≤Δ*. Thus, the gaze position at time instant t₁ continues to be the reference gaze position. The visual-fixation count κ is increased to 3 (process 8462). Since κ<κ_(min), no action is taken and the refresh module continues from process 8465 to steps 8450, 8452, 8456, and 8456.

At time instant t₄, process 8458 determines that the displacement Δ_(1,4) of a gaze position from the reference gaze position is ≥Δ*. Thus, the gaze position at time instant t₁ continues to be the reference gaze position. The visual-fixation count κ is increased to 4 (process 8462). Since κ=κ_(min), process 8472 forms a control message containing the cyclic frame number determined in process 8452 and the current gaze position determined at process 8454. Process 8378 transmits the control message to view adaptor 8220 then revisits processes 8450, 8452, 8454, 8456, and 8458.

Cluster 8530A of gaze positions captured at time instants {t₁, t₂, t₃, t₄} is treated as a single gaze position corresponding to the gaze position at time instant t₁, termed a reference position 8525A for cluster 8530A.

At time instant t₅, process 8458 determines that the displacement Δ_(1,5) of a gaze position from the reference gaze position is greater than Δ*. Thus, the gaze position at time instant t₅ becomes the reference gaze position (process 8461) and the visual-fixation count κ is set to 1 (process 8463). Since κ is less than κ_(min), process 8465 leads to processes 8450, 8452, 8454, 8456, and 8458.

At time instant t₆, process 8458 determines that the displacement Δ_(5,6) of a gaze position from the reference gaze position corresponding to gaze time t₅ is greater than Δ*. Thus, the gaze position at time instant t₆ becomes the reference gaze position (process 8461) and the visual-fixation count κ is set to 1 (process 8463). Since κ is less than κ_(min), process 8465 leads to processes 8450, 8452, 8454, 8456, and 8458.

At time instant t₇, process 8458 determines that the displacement Δ_(6,7) of a gaze position from the reference gaze position is greater than Δ*. Thus, the gaze position at time instant t₇ becomes the reference gaze position (process 8461) and the visual-fixation count κ is set to 1 (process 8463). Since κ is less than κ_(min), process 8465 leads to processes 8450, 8452, 8454, 8456, and 8458. Continuing in the same fashion, the cluster of gaze positions captured at time instants {t₇, t₈, t₉, t₁₀, t₁₁} is treated as a single gaze position corresponding to the gaze position at time instant t₇.

Cluster 8530B of gaze positions captured at time instants {t₇, t₈, t₉, t₁₀, t₁₁} is treated as a single gaze position corresponding to the gaze position at time instant t₇, termed a reference position 8525B for cluster 8530B.

Cluster 8530C of gaze positions captured at time instants {t₁₂, t₁₃, t₁₄, t₁₅} is treated as a single gaze position corresponding to the gaze position at time instant t₁₂, termed a reference position 8525C for cluster 8530C. Cluster 8530D of gaze positions captured at time instants {t₁₆, t₁₇, t₁₈, t₁₉} is treated as a single gaze position corresponding to the gaze position at time instant t₁₆, termed a reference position 8525D for cluster 8530D.

Clusters 8530A, 8530B, 8530C, and 8530C of respective adjacent gaze positions represent view regions of interest. An isolated gaze position 8540, i.e., a gaze positions that is not close to a preselected number of other gaze positions, within a predefined observation period, are treated as detection noise and ignored. Thus, the gaze positions 8540A and 8540B, detected at time instants t₅ and t₆, respectively are considered to represent view regions of no interest.

Optionally, rather than using a first gaze position of a cluster to represent the cluster, the centroid of all gaze positions of the cluster may be used to represent the cluster. This, however necessitates reporting the cluster to the high-capacity view adaptor 8220 after formation of the entire cluster which, in turn, requires retaining more frames at a circular content-buffer as will be described with reference to FIG. 97 and FIG. 100 .

FIG. 86 illustrates an example 8600 of selected view regions (view windows) 8650 based on the method of FIG. 84 for a fixation threshold of 1 (κ_(min)=1). Six view regions 8650(1) to 8650(6) are illustrated. With a fixation index of 1, view regions 8650 (view windows 8650) are defined for isolated gaze positions at time instants t₀ and t₆. The arrows 8670(1) to 8670(5) indicate the sequence of defining the view regions 8650(2) to 8665(6).

FIG. 87 illustrates an example 8700 of selected view regions (view windows) 8650 based on the method of FIG. 84 for a fixation threshold of 4 (κ_(min)=4). With a fixation threshold of 4, no view regions are generated around isolated gaze positions. Only view regions 8650(1), 8650(4), 8650(5), and 8650(6) are selected (referenced as 8750(1) to 8750(4), respectively). The arrows 8770 indicate the sequence of defining the view regions.

FIG. 88 illustrates an example 8800 of detected gaze positions for a case of close clusters 8830 of adjacent gaze positions. According to the method of content selection of FIG. 84 , with a visual-fixation threshold κ_(min)=5, isolated gaze positions 8810 (such as 8810A and 8810B) would be omitted if the visual-fixation threshold is greater than 1, and gaze positions of insignificant clusters 8820 (such as 8820A and 8820B) would be omitted if the visual-fixation threshold κ_(min) is selected to be greater than 4. The gaze positions of clusters 8830(1) to 8830(11) of the field of view are of interest and are communicated to the high-capacity view adaptor 8220 as successive overlapping view regions (view windows).

FIG. 89 illustrates an example 8900 of selected view regions (view windows) 8950 of the view field of FIG. 88 according to the method of FIG. 84 with a fixation threshold of 5 (κ_(min)=5). With κ_(min)=5, the isolated gaze positions are not considered while adjacent gaze positions are grouped in 11 clusters 8830 individually identified according to respective reference positions 8930(1) to 8930(11). Overlapping view regions (view windows) 8950(1) to 8950(11) are computed at the high-capacity view adaptor 8220 (module 10520 of FIG. 105 and FIG. 106 ).

FIG. 90 illustrates a further example 9000 of selection of pivotal gaze-points selection, based on the method of FIG. 84 , for another case of sparse clusters of adjacent gaze positions. Two-dimensional gaze positions indicated in a view field are captured at time instants t₁, . . . , t₆₈. A reference gaze position 9005 is initialed to be the center of a display area corresponding to an arbitrary time instant to. The gaze positions are preferably captured at regular intervals, every eight frame periods, for example, as mentioned earlier. The visual-fixation threshold, κ_(min), is selected to equal 1. Thus, isolated gaze positions 9010, which are the gaze positions P₁, P₂, P₁₃ to P₁₇, P₂₈, P₂₉, P₃₉ to P₄₂, P₅₁ to P₅₅, and P₆₆ to P₆₈ are considered.

Five clusters 9030A, 9030B, 9030C, 9030D, and 9030E of adjacent gaze positions, corresponding to reference gaze positions P₃, P₁₈, P₃₀, P₄₃, and P₅₆, are identified.

Gaze Reference |P-R| > Visual Control Control Position position Δ* fixation message message P R ? κ κ_(min) = 1 κ_(min) = 5 P₁  P₀  Y 1 P₁  — P₂  P₁  Y 1 P₂  — P₃  P₂  Y 1 P₃  — P₄  P₃  N 2 — P₅  N 3 — P₆  N 4 — P₇  N [5] — P₈  N [6] P₃  P₉  N [7] — P₁₀ N [8] — P₁₁ N [9] — P₁₂ N [10]  — P₁₃ Y 1 P₁₃ — P₁₄ P₁₃ Y 1 P₁₄ — P₁₅ P₁₄ Y 1 P₁₅ — P₁₆ P₁₅ Y 1 P₁₆ — P₁₇ P₁₆ Y 1 P₁₇ — P₁₈ P₁₇ Y 1 P₁₈ — P₁₉ P₁₈ N 2 — P₂₀ N 3 — P₂₁ N 4 — P₂₂ N [5] — P₂₃ N [6] P₁₈ P₂₄ N [7] — P₂₅ N [8] — P₂₆ N [9] — P₂₇ N [10]  — P₂₈ Y 1 P₂₈ — P₂₉ P₂₈ Y 1 P₂₉ — P₃₀ P₂₉ Y 1 P₃₀ — P₃₁ P₃₀ N 2 — P₃₂ N 3 — P₃₃ N 4 — P₃₄ N [5] — P₃₅ N [6] P₃₀ P₃₆ N [7] — P₃₇ N [8] — P₃₈ N [9] — P₃₉ P₃₀ Y 1 P₃₉ — P₄₀ P₃₉ Y 1 P₄₀ — P₄₁ P₄₀ Y 1 P₄₁ — P₄₂ P₄₁ Y 1 P₄₂ — P₄₃ P₄₂ Y 1 P₄₃ — P₄₄ P₄₃ N 2 — P₄₅ N 3 — P₄₆ N 4 — P₄₇ N [5] — P₄₈ N [6] P₄₃ P₄₉ N [7] — P₅₀ N [8] — P₅₁ Y 1 P₅₁ — P₅₂ P₅₁ Y 1 P₅₂ — P₅₃ P₅₂ Y 1 P₅₃ — P₅₄ P₅₃ Y 1 P₅₄ — P₅₅ P₅₄ Y 1 P₅₅ — P₅₆ P₅₅ Y 1 P₅₆ — P₅₇ P₅₆ N 2 — P₅₈ N 3 — P₅₉ N 4 — P₆₀ N [5] — P₆₁ N [6] P₅₆ P₆₂ N [7] — P₆₃ N [8] — P₆₄ N [9] — P₆₅ N [10]  — P₆₆ Y 1 P₆₆ — P₆₇ P₆₆ Y 1 P₆₇ — P₆₈ P₆₇ Y 1 P₆₈ — Table indicating selection of view regions based on detected gaze positions

Results of application of the method to the example of FIG. 90 , with κ_(min)>1, are illustrated in the table, below, indicating selection of view regions based on detected gaze positions. The first column lists all detected gaze positions, denoted P₁ to P₆₈, over a time period. The second column lists corresponding reference positions. The third column lists the distance between each detected position and corresponding reference position. The fourth column list a count of visual fixation corresponding to each detected gaze position. The fifth column identifies gaze positions leading to sending a control message to the high-capacity view adaptor 8220 (FIG. 84 , process 8472) for a case where κ_(min) is set to 1. The last column identifies gaze positions leading to sending a control message to the high-capacity view adaptor 8220 (FIG. 84 , process 8472) for a case where κ_(min) is set to 5. As indicated for the case of κ_(min)=1, pivotal gaze positions P₃, P₁₈, P₃₀, P₄₃, and P₃₆ as well as isolated gaze positions P₁, P₂, P₁₃ to P₁₇, P₂₈, P₂₉, P₃₉ to P₄₂, P₅₁ to P₅₅, and P₆₆ to P₆₈ are considered for forming view regions. For the case of κ_(min)=5, only the pivotal gaze positions are considered.

For the case of κ_(min)=5, each of pivotal gaze positions P₃, P₁₈, P₃₀, P₄₃, and P₅₆ is reported to the high-capacity view adaptor after a delay of 5 inter-gaze periods. This is taken into account at the high-capacity view adaptor 8220.

FIG. 91 illustrates specific gaze positions 9100 used for computing view regions, for the case of sparse clusters of adjacent gaze positions of FIG. 90 with the visual-fixation threshold κ_(min) of 1. With κ_(min)=1, view regions (view windows) are computed for reference gaze positions 9130 as well as isolated gaze positions 9110 labeled P₁, P₂, P₁₃ to P₁₇, P₂₈, P₂₉, P₃₉ to P₄₂, P₅₁ to P₅₅, and P₆₆ to P₆₈.

FIG. 92 illustrates specific gaze positions 9200 used for computing view regions, for the case of sparse clusters of adjacent gaze positions of FIG. 90 with the visual-fixation threshold κ_(min) set to be greater than 1. With κ_(min)>1, view regions (view windows) are computed only for reference gaze positions 9130A to 9130E, which are P₃, P₁₈, P₃₀, P₄₃, and P₅₆.

FIG. 93 illustrates reference gaze positions 9300 for the case of sparse clusters of adjacent gaze positions of FIG. 90 according to different criteria.

Table 9310 indicates the initialized gaze position, P₀, and all detected gaze positions, P₁ to P₆₈ over an observation period. A view region would be defined for each of the 68 detected gaze positions if visual-fixation is not taken into account.

Table 9320 indicates the isolated gaze positions and reference gaze positions as illustrated in FIG. 91 . A view region would be defined for each of the reference gaze positions 9322 (P₃, P₁₈, P₃₀, P₄₃, and P₅₆) for the durations of corresponding clusters of adjacent gaze position, as well as the isolated gaze positions 9321 if the visual-fixation threshold is set to 1 (κ_(min)=1). The duration of a cluster is determined as the number of gaze positions of the cluster times the gaze-detection period (of 8 frames, for example).

Table 9330 indicates reference gaze positions as illustrated in FIG. 92 . A view region would be defined for each of the reference gaze positions 9322 (P₃, P₁₈, P₃₀, P₄₃, and P₅₆). The duration 9332 of a view region for a current reference gaze position is determined according to the number of gaze positions between the start of the current reference gaze position and the start of an immediately succeeding gaze position.

FIG. 94 illustrates an example 9400 of timing of sending control messages from the enhanced refresh module 9620 (FIG. 96 ) of the enhanced content controller 8210 to the high-capacity view adaptor 8220. The detected gaze positions are labelled as P_(j), j>0. As mentioned earlier, gaze positions are detected at regular time intervals, of eight frame periods, for example. A first cluster of adjacent gaze positions has a duration of 9410A, starting with gaze position P₁₀₀ and ending with gaze position P₁₁₆. A second cluster of gaze positions has a duration of 9410B, starting with gaze position P₁₂₄ and ending with gaze position P₁₄₅.

With a visual-fixation threshold κ_(min)=5, the enhanced refresh module 9620 of the enhance content controller 8210 sends a control message 9430A, at the start of detecting gaze position P₁₀₅, to the high-capacity view adaptor 8220 indicating detection of a significant cluster. Reference numeral 9420A marks the time instants of start of gaze positions P₁₀₀. Reference numeral 9421A marks reaching κ_(min) gaze positions, just prior to detecting gaze position P₁₂₉. Reference numeral 9422A marks detecting the last gaze position within the cluster.

The refresh module sends a control message 9430B, at the start of detecting gaze position P₁₂₉, to the high-capacity view adaptor 8220 indicating detection of a new significant cluster. Reference numeral 9420B marks the time instants of start of gaze positions P₁₂₄. Reference numeral 9421B marks reaching κ_(min) gaze positions, just prior to detecting gaze position P₁₂₉. Reference numeral 9422B marks detecting the last gaze position within the new cluster.

The intermediate gaze positions detected during the time gap between gaze position P₁₁₆ and gaze position P₁₂₄ may be isolated gaze positions or gaze positions belonging to insignificant clusters which are ignored (treated as noise). The view region (view window) corresponding to the cluster starting with gaze position P₁₀₀ lasts until the start of gaze position P₁₂₄ (of duration 9460A covering gaze positions P₁₀₀ to P₁₂₃). Likewise, the view region corresponding to cluster starting with gaze position P₁₂₄ lasts until the start of gaze position P₁₅₀ (of duration 9460B covering gaze positions P₁₂₄ to P₁₄₉).

The enhanced content controller 8210 detects adjacent gaze positions P₁₀₀ to P116. Applying the method of FIG. 84 , with κ_(min)=5, at instant 9420A the enhanced content controller designates gaze positions P₁₀₀ to P₁₀₄ as a kernel of a cluster 9410A with position P₁₀₀ as a respective reference position (pivotal position). The enhanced content controller 8210 sends a control message 9430A, following detection of P₁₀₄, to the high-capacity view adaptor 8220 indicating a significant gaze position starting at position P₁₀₀. Detected gaze positions P₁₀₅ to P116 are found to be adjacent to reference gaze position P₁₀₀, hence belonging to the same cluster 9410A.

A detected gaze position P₁₁₇ is found to be distant from the reference gaze position P₁₀₀, hence the formed cluster 9410A contains 17 gaze positions P₁₀₀ to P116. Detected gaze position P₁₁₇ may be: (1) an isolated gaze position; (2) a start of an insignificant cluster having less than κ_(min) gaze positions; or (3) the start of a new significant gaze position. In the illustrated example, P₁₁₇ does not start a new significant cluster.

The enhanced content controller 8220 detects adjacent gaze positions P₁₂₄ to P₁₄₅. Applying the method of FIG. 84 , with κ_(min)=5, the enhanced content controller 8210 designates gaze positions P₁₂₄ to P128 as a kernel of a cluster 9410B with position P₁₂₄ as a respective reference gaze position. Following detection of P128, the enhanced content controller 8210 sends a control message 9430B to the high-capacity view adaptor 8220 indicating a significant gaze position starting at position P₁₂₄. Detected gaze positions P₁₂₉ to P₁₄₅ are found to be adjacent to reference gaze position P₁₂₄, hence belonging to the cluster 9410B.

A detected gaze position P₁₄₆ is found to be distant from the reference gaze position P₁₂₄, hence the formed cluster 9410B contains 22 gaze positions P₁₂₄ to P₁₄₅. P₁₄₆ may be: (1) an isolated gaze position; (2) a start of an insignificant cluster having less than κ_(min) gaze positions; or (3) the start of a new significant gaze position. In the illustrated example, P₁₄₆ does not start a new significant cluster. Later, detected gaze position P₁₅₀ starts a new significant gaze position.

FIG. 95 illustrates an example 9500 of selection of pivotal gaze-points selection, based on the method of FIG. 84 for another case of sparse clusters of adjacent gaze positions. Two-dimensional gaze positions P₁, . . . , P₇₅ are detected. A reference gaze position 9510 is initialed to be the center of a display area, corresponding to an arbitrary time instant to. The gaze positions are preferably captured at regular intervals, every eight frame periods, for example. The visual-fixation threshold, κ_(min), is selected to equal 5. A cluster of close gaze positions having less than a predetermined number, κ_(min), of gaze positions may be skipped. Thus, isolated gaze positions 9520, which are the gaze positions P₁, P₂, P₁₃, P₁₄, P₁₅, P₂₀, P₃₃, P₄₃, P₄₇, P₄₈, P₅₇, P₅₈, P₆₁, P₆₂, and P₇₃ to P₇₅ are treated as detection noise and omitted. Insignificant clusters 9520A, 9520B, 9520C, and 9520D, each having less than κ_(min) adjacent gaze positions, are also treated as detection noise and omitted.

With κ_(min)=5, five clusters 9530A, 9530B, 9530C, 9530D, and 9530E of adjacent gaze positions, corresponding to reference gaze positions P₃, P₂₁, P₃₄, P₄₉, and P₆₃, are identified.

FIG. 96 illustrates means 9600 of control-data transfer from the enhanced content controller 8210 to the high-capacity view adaptor 8220. The enhanced content controller comprises an enhanced refresh module 9620 which filters detected gaze positions based on visual-fixation of an operator 4725 viewing a panoramic display. Enhanced refresh module 9620 comprises a module for determining visual fixation. The refresh module may send content-selection commands to the high-capacity view adaptor through a dedicated path, a high-priority path through a network 9650, or a shared path through the network. Data transfer through a dedicated path would be delay-jitter-free. Data transfer through a high-priority path may be subject to minor delay jitter. Data transfer through a shared path may be subject to considerable delay jitter which necessitates means for offsetting the effect of jitter at the high-capacity view adaptor 8220 as illustrated in FIG. 100 .

FIG. 97 illustrates examples 9700 of temporal discrepancy between receiving of frame content data and receiving corresponding control data at the high-capacity view adaptor 8202 for the configurations of FIG. 82 and FIG. 83 .

For the configuration of FIG. 82 of collocated acquisition module 4720, enhanced content filter 8210, and high-capacity view adaptor 8220, the acquisition module 4720 concurrently supplies identical baseband pure multimedia signals 4730A and 4730B to the enhanced content controller 8210 and the high-capacity view adaptor 8220 along local paths 8260A and 8260B, respectively. Enhanced refresh module 9620 of the enhanced content controller sends to the high-capacity view adaptor (path 8240) an indication of a reference position of a significant cluster of gaze positions after a delay 9720 Δ₀ equal to the predefined visual-fixation threshold κ_(min) times the gaze detection period (of eight frame periods, for example). Thus, the high-capacity view adaptor buffers content data over a moving time window of a duration 9740A that equals or exceeds Δ₀.

For the case of a spatially distributed content-filtering system of FIG. 83 , an acquisition module 4720A is collocated with the enhanced content controller and an acquisition module 4720B is collocated with the high-capacity view adaptor 8220. In one implementation, a panoramic signal source 4710 sends identical modulated carriers 4712A and 4712B of the baseband pure signal to the enhanced content controller 8210 and the high-capacity view adaptor 8220. In an alternate implementation, the panoramic signal source sends a modulated carrier 4712B of the baseband pure signal to the high-capacity view adaptor 8220 but sends a modulated carrier 4712A of a frame-sampled pure signal that is sufficient for an operator to select reference gaze positions of significant clusters.

Acquisition module 4720A supplies a baseband pure signal (or a frame sampled baseband pure signal) 4730C to the enhanced content controller 8210. Enhanced refresh module 9620 of the enhanced content controller 8210 sends to the high-capacity view adaptor (path 8340) an indication of a reference position of a significant cluster of gaze positions after a delay 9720 Δ₀ equal to the predefined visual-fixation threshold κ_(min) times the gaze detection period. The transfer delays from the panoramic source to the enhanced content controller 8210, from the panoramic source to the high-capacity view controller, and from the enhanced content controller to the high-capacity view adaptor, are denoted Δ₁, Δ₂, and Δ₃ respectively. The high-capacity view adaptor buffers content data over a moving time window of a duration 9740B that equals or exceeds |Δ₀+Δ₁+Δ₃−Δ₂|.

FIG. 98 illustrates an example 9800 of transfer delay along a contention-free path from the enhanced content controller 8210 to the high-capacity view adaptor 8220 for a first case where the enhanced content controller 8210 is collocated with the high-capacity view adaptor 8220 and a second case where the enhanced content controller 8210 has a dedicated path to the high-capacity view adaptor 8820, the dedicated path incurring a significant propagation delay, δ₀, but without delay jitter.

Control messages 9810 sent from the enhanced refresh module 9620 correspond to reference gaze positions. The time period between a control message relevant to reference position R_(j) and an immediately succeeding control message relevant to reference position R_((j+1)), j>0, depends on the number of detected gaze positions that reference position P_(j) represents. In the illustrated example, reference gaze positions R₀₀, R₀₁, R₀₂, R₀₃, and R₀₄ correspond to frames f₄₉₆, f₆₄₀, f₈₀₀, f₉₈₄, and f₁₁₂₀. Thus, reference positions R₀₀, R₀₁, R₀₂, and R₀₃ represent 144, 160, 184, 136 frame periods, respectively

For the first case, control messages 9810 are received at the high-capacity view adaptor 8220 after an insignificant delay, such as a small fraction of a frame period (of 20 milliseconds or, so). For the second case, control messages 9810 are received at the high-capacity view adaptor after a delay δ₀, which may be of the order of several frame periods.

FIG. 99 illustrates an example 9900 of transfer delay along a shared-network path from the enhanced content controller 8210 to the high-capacity view adaptor 8220 for a third case where the path incurs low delay jitter and a fourth case where the path incurs high delay jitter. Control messages 9920A, from the enhanced content controller to the high-capacity view adaptor, are subjected to transfer delays δ⁽¹⁾ ₁, δ⁽¹⁾ ₂, δ⁽¹⁾ ₃, . . . , of relatively low variance. Control messages 9920B are subjected to transfer delays δ⁽²⁾ ₁, δ⁽²⁾ ₂, δ⁽²⁾ ₃, . . . , of relatively high variance.

FIG. 100 illustrates an example 10000 of data organization in a circular content buffer 10010 and a corresponding circular control buffer 10040 used for pairing frame-content data and corresponding view-region definitions. FIG. 101 is a continuation of FIG. 100 .

The circular-content buffer 10010 holds content data of sequential frames within a moving time-window of 32 frame periods. The figure illustrates the occupancy state of the circular content-buffer immediately after the first 32 frames. In the illustrated example, gaze positions are detected at regular intervals of 4 frame periods each. Thus, the circular control buffer holds control data for 8 clusters of four frames each.

Starting with an empty content buffer, the content of each of 32 successive frames f₀₀ to f₃₁ is written in a respective memory section 10020, thus fully populating the circular content buffer. The content of each subsequent frame overwrites a previously written frame. The residence time in the circular buffer of the content of any frame is 32 times the duration of a frame. For example, if the frame rate is 32 frames/second, the residence time is one second; the residence time being the period between writing content of a frame and overwriting the content. Thus, the content of frame f₃₂ overwrites the content of frame f₀₀, the content of frame f₃₃ overwrites the content of f₀₁, the content of frame 50 overwrites the content of frame 18, and so on. When frame f₅₀ is written (FIG. 101 ), the circular content buffer contains content data of frames f₁₉ to f₅₀ as indicated in FIG. 101 . The entries 10130 in the circular buffer corresponding to consecutively detected gaze positions, P_(j), j>0, are indicated.

FIG. 102 illustrates a high-throughput content filter 10200 implemented as a bank of content-filtering units 10240, operating concurrently, each coupled to a respective buffer 10250, of a bank of buffers, for holding content-filtered frames. The number, N, N>1, of content-filtering units 10240 is determined based on the processing time per frame per content-filtering unit. Baseband frame data 10210, derived from pure video signal 4730B (FIG. 82 ) or 4730D (FIG. 83 ), together with data 10212 defining frame-specific view boundaries are cyclically supplied from input port 10220 to the bank of content-filtering units through a selector 10225 of a 1:N cyclical-access mechanism 10230. An output port 10270 cyclically receives content-filtered frames 10280 from the buffers 10250 through a selector 10255 of an N:1 cyclical access mechanism 10260. Content-filtered frames 10280 are sent to a respective destination (or multiple destinations). The baseband frame data 10210 (4730B, FIG. 82 , or 4830D, FIG. 83 ) comprises frame content data as well as relevant metadata.

Each content-filtering unit 10240 performs processes of extracting pixels within the view boundary of each frame to produce frame segments of interest. The frame segments are reframed, according to a specified frame format, to form the content-filtered frames. The content-filtered frames may be compressed prior to dissemination. The minimum number, N, of content filtering units is determined as a ratio of evaluated processing time per frame per content-filtering unit to a frame duration.

FIG. 103 illustrates an example 10300 of processing durations of concurrent content filtering of successive frames 10310, of which frames f₀₀ to f₂₄ are illustrated. In the illustrated example, the processing time per frame, denoted τ_(f), within a single content-filtering unit 10240 is determined to be approximately 3.7 times a frame period. Thus, the high-throughput content filter 10100 employs four (┌3.7┐) content-filtering units to be able to handle a continuous stream of frames. Frame content data 10320, denoted u₀₀ to u₂₄, extracted at the acquisition module 4720 are cyclically distributed to individual content-filtering units of the bank of four content-filtering units 10240. Thus, each content-filtering unit 10240(j) processes data of a respective set 10320(j) of frame-content data, j≥1. Filtered frame content data 10340, denoted w₀₀ to w₂₄, are directed to port 10270 of the high-throughput content filter 10200.

FIG. 104 illustrates details 10400 of processed successive frames at separate content-filtering units 10240, indicating a sequence 10410 of pure frame-content data 10320 to be processed at each content-filtering unit 10240, a sequence 10420 of filtered frame-content data 10340 at output of a content-filtering unit, and filtered content data 10430 read from a buffer 10250 holding output of a content-filtering unit. Thus:

-   -   content-filtering unit 10240(1) receives pure frame-content data         u₀₀, u₀₄, u₀₈ and u₁₂ and produces filtered frame-content data         w₀₀, w₀₄, w₀₈ and w₁₂;     -   content-filtering unit 10240(2) receives pure frame-content data         u₀₁, u₀₅, u₀₉ and u₁₃ and produces filtered frame-content data         w₀₁, w₀₅, w₀₉, and w₁₃;     -   content-filtering unit 10240(3) receives pure frame-content data         u₀₂, u₀₆, u₁₀, and u₁₄ and produces filtered frame-content data         w₀₂, w₀₆, w₁₀, and w₁₄; and     -   content-filtering unit 10240(4) receives pure frame-content data         u₀₃, u₀₇, u₁₁, and u₁₅ and produces filtered frame-content data         w₀₃, w₀₇, w₁₁, and w₁₅.

FIG. 105 is a schematic 10500 of a high-capacity view adaptor 8220A configured to process content-control messages received from the enhanced content controller 8210 over a jitter-free path. The view-adaptor comprises:

-   -   (i) a refresh-module interface 10510;     -   (ii) a module 10520 for computing a view boundary surrounding a         reference gaze position;     -   (iii) a logical on-off switch 10522;     -   (iv) a memory device 10530 holding time-varying view boundary;     -   (v) a circular content buffer 10010;     -   (vi) a logical combiner 10540; and     -   (vii) a high-throughput content filter 10200

The refresh-module interface 10510 is configured to receive data relevant to reference gaze positions from the enhanced refresh module 9620 of enhanced content controller 8810 indicating respective frame indices and relevant metadata.

Module 10520 comprises software instructions for computing a new view boundary (view window) only when a received reference gaze position differs from an immediately preceding reference gaze position. In an implementation, the enhanced refresh module 9620 sends an indication of a frame index and a corresponding reference position during each frame period (of 20 milliseconds, for example). In an alternative implementation, the enhanced refresh module 9620 sends the tuple {frame index, current reference position, inter-gaze period} when a new reference position is determined, but sends a tuple {frame index, null, null} otherwise.

Memory device 10530 contains a definition of a current view boundary (a current view window) which is updated only, through logical on-off switch 10522, when module 10520 receives a new reference position. The content of the memory is read during each frame period and supplied to the high-throughput content filter 10200 through (logical) combiner 10540.

The circular content buffer 10010 stores source frame content data extracted from the pure video signal 4730B (FIG. 96 ) over a moving window of at least an integer number, ϕ, of frames, where ϕ equals ((κ_(min)×ν)+┌D_(t)/f_(t)┐+1), where ν is the inter-gaze number of frames (eight, for example), f_(t) the frame period, D_(t) is a known transfer delay through path 9622. A guard time of one frame period is added. Contents of successive source frames are supplied to a content-filtering unit 10240 through (logical) combiner 10540. For example, for κ_(min)=5, ν=6, D_(t)=0.0, 0=30. For κ_(min)=8, ν=8, ┌D_(t)/f_(t)┐=18, ϕ=82. Device 10800 of FIG. 108 implements high-capacity view adaptor 8220A.

FIG. 106 is a schematic 10600 of a high-capacity view adaptor 8220B configured to process content-control messages received from the enhanced content controller 8210 over a path incurring delay jitter. The main difference from high-capacity view adaptor 8220A is the placement of a circular-control buffer 10400 between the refresh module interface and module 10520 to overcome the effect of delay jitter at the expense of increased storage at the circular content buffer 10010. Device 10900 of FIG. 109 implements high-capacity view adaptor 8220B.

FIG. 107 illustrates timing 10700 of content-filtering processes for a single content-filtering unit 10240. Module 10520 acquires (process 10710) gaze-position data, including successive reference gaze positions 10712, from the enhanced refresh module 9620, computes respective boundary definition 10722 of view regions, and accesses memory device 10530 (process 10720). Module 10520 computes a boundary definition for a reference point which is presented to memory device 10530 after a computing time δ_(c) (reference 10714). A content-filtering unit reads boundary-definition data from memory 10430 (δ_(a) reading interval) and performs process 10730 to form filtered frame content 10732.

FIG. 108 illustrates a device 10800 implementing high-capacity view adaptor 8220A (schematic of FIG. 105 ). The device comprises a processor 10820, which may comprise multiple processing units, coupled memory devices storing software instructions and memory devices storing intermediate content data and control data.

The memory devices storing software instructions form:

-   -   (a) a coordination module 10810;     -   (b) module 10520 for computing view boundary, defining a view         region (view window)     -   (c) an interface 10830 to an acquisition module 4720;     -   (d) interface to refresh module 9620; and     -   (e) an interface 10850 to a bank of content-filtering units         10240.

The memory devices storing intermediate data comprise a circular-content buffer 10010 and a buffer 10530 holding view-region definitions. The processes performed at device 10810, under the direction of coordination module 10810, are illustrated in FIG. 110 .

FIG. 109 illustrates a device 10900 implementing high-capacity view adaptor 8220B (schematic of FIG. 106 ). The main difference between device 10900 and device 10800 is the use of circular control buffer 10040 to handle variable temporal discrepancy between acquisition of frame-content data from an acquisition module and acquisition of corresponding view-region-definition data from the enhanced refresh-module 9620. Consequently, coordination module 10910 includes instructions for handling the circular control buffer. The processes performed at device 10810, under the direction of coordination module 10910, are illustrated in FIG. 111 .

FIG. 110 illustrates processes performed at device 10800 under direction of coordination module 10810.

Process 11010 receives frame-indexed content data from acquisition module 4720 (FIG. 82 ). As described earlier, a cyclical frame index is associated with each video frame. Process 11020 places frame-content data into circular buffer, overwriting previous data of expired residence time as described in FIG. 100 . Process 11010 and 11020 continue repeatedly as indicated with the circular arrow “A”. Process 11020 fans out to both process 11010 and 11080.

Process 11050 receives a reference gaze position and a respective frame index from refresh module 9620. Process 11060 directs the reference gaze position to view-boundary model 10520. Process 11050 and 11060 continue repeatedly as indicated with the circular arrow “B”. Process 11060 fans out to both process 11050 and 11070. Process 11070 receives view-region definition from module 10520 and places the definition in buffer 10530.

Process 11080 accesses the circular content buffer to acquire content data corresponding to the reference frame index. Process 11090 directs view-region definition available from process 11070 and content data available from process 11080 to a content-filtering unit 10240, through interface 10850, to produce content-filtered frames 10280 which are sent to a respective destination (or multiple destinations) as illustrated in FIG. 102 .

FIG. 111 illustrates processes performed at device 10900 under direction of coordination module 10910.

As in device 10800, process 11010 receives frame-indexed content data from acquisition module 4720 (FIG. 82 ). Process 11020 places frame-content data into circular buffer, overwriting previous data of expired residence time as described in FIG. 100 . Process 11010 and 11020 continue repeatedly as indicated with the circular arrow “A”. Process 11020 fans out to both process 11010 and 11080.

Process 11050 receives a reference gaze position and a respective frame index from refresh module 9620. Process 11140 places the reference gaze position and respective frame index in the circular control buffer 10040. Process 11050 and 11140 continue repeatedly as indicated with the circular arrow “C”. Process 11140 fans out to both process 11050 and 11150.

Process 11150 reads a stored reference gaze position and corresponding stored frame index from circular control buffer 10040. Process 11160 directs the stored reference gaze position to view-boundary model 10520. Process 11150 and 11160 continue repeatedly as indicated with the circular arrow “D”. Process 11160 fans out to both process 11150 and 11070. Process 11070 receives view-region definition from module 10520 and places the definition in buffer 10530.

Process 11080 accesses the circular content buffer to acquire content data corresponding to the stored frame index. Process 11090 directs view-region definition available from process 11070 and content data available from process 11080 to a content-filtering unit 10240, through interface 10850, to produce content-filtered frames 10280 which are sent to a respective destination (or multiple destinations) as illustrated in FIG. 102 .

FIG. 112 illustrates a variation 11200 of the spatially distributed content-filtering system 8300. System 11200 comprises:

-   -   (1) first acquisition module 4720A configured to receive a         source signal (a modulated carrier) from a panoramic signal         source and generate a baseband panoramic signal 4730C organized         into indexed frames;     -   (2) second acquisition module 4720B configured to generate a         replica 4730D of the baseband panoramic signal 4730C;     -   (3) a repeater 11220, collocated with the enhanced content         controller 8210, for retransmitting the modulated carrier         received at the first acquisition module to the second         acquisition module over path 11240;     -   (4) enhanced content controller 8210 collocated with the first         acquisition module;     -   (5) high-capacity view adaptor 8220 collocated with the second         acquisition module; and     -   (6) compression and transmission module 8280 the functions of         which may, alternatively, be embedded within the high-capacity         view adaptor 8220.

The content controller 8210 comprises:

-   -   (a) a device for producing a panoramic display of the baseband         panoramic signal; and     -   (b) enhanced refresh module 9620 (FIG. 96 ) configured to         measure durations of visual fixations of a viewer of the         panoramic display, based on detecting the viewer's gaze         positions, and determining a pivotal gaze position and a         respective pivotal frame index for each visual fixation         attaining a prescribed duration threshold.

The high-capacity view adaptor 8220 comprises:

-   -   (a) module 10520 (FIG. 105 ) for computing a boundary of a view         region, of prescribed shape and dimensions, surrounding the         pivotal gaze position;     -   (b) circular content buffer 10010 for holding content data of         the replica 4730D of the baseband panoramic signal 4730C over a         moving time window spanning a predefined number of frame         periods;     -   (c) array 10200 (FIG. 102 ) of content-filtering units 10240         operating concurrently to extract segments, corresponding to the         view region, of specific frames of the replica of the baseband         panoramic signal starting with a frame of the respective pivotal         frame index and ending upon determining a new pivotal frame         index of a subsequent pivotal gaze position     -   (d) a first cyclical-access mechanism 10230 for sequentially         transferring the specific frames of the baseband panoramic         signal to individual content-filtering units of the array of         content-filtering units as illustrated in FIG. 104 ; and     -   (e) a second cyclical-access mechanism 10260 for sequentially         transferring the filtered frames to a respective destination.

Each content-filtering unit 10240 is configured to reframe an extracted segment according to a specified frame format to produce a filtered frame. A content-filtering unit 10240 may also be configured to compress filtered frames which modulate a downstream carrier to transmission to respective destinations.

The main difference between the system of FIG. 112 and the system of FIG. 83 is that in the system of FIG. 83 the second acquisition module 472B receives the source signal directly from the panoramic signal source while in the system of FIG. 112 the second acquisition module receives a replica of the source signal supplied to the first acquisition module through a repeater, resulting in a significant reduction of transfer delay as illustrated in FIG. 113 and FIG. 114 .

The circular content buffer is provisioned to store frame content data extracted from the baseband panoramic signal over a moving time window spanning an integer number, ϕ*, of frames determined as:

ϕ*=┌(κ_(min)×ν)+(Δ₃−Δ₄)/f _(t))+1┐, including a guard time of one frame period.

As described earlier, κ_(min) is a count of successive adjacent gaze positions within the prescribed duration threshold, where the pairwise displacement of any pair of gaze-positions is within a predefined proximity threshold, ν is a predefined inter-gaze number of frames, f_(t) is a frame duration (e.g., 20 milliseconds), Δ₃ is a transfer delay of a pivotal gaze position from the content controller to the view adaptor, and Δ₄ is a transfer delay from the repeater to the view adaptor along path 11240.

FIG. 113 illustrates an example 11300 of temporal discrepancy between receiving of frame content data and receiving corresponding control data at the high-capacity view adaptor for the configurations of FIG. 112 . Both the enhanced content controller 8210 and the repeater 11220 receive the source signal, over path 8304A. Repeater 11220 retransmits the source signal along a path 11240 incurring a delay of Δ₄ time-units. The content controller detects each significant visual fixation that attains a prescribed duration threshold covering the prescribed number κ_(min), κ_(min)≥1, of successive adjacent gaze positions, and sends respective pivotal position data to the high-capacity view adaptor along a path 8340, incurring a transfer delay Δ₃. Paths 8340 and 11240 may be established through a same network; transfer delays Δ₃ and Δ₄ may be substantially equal. Thus, the temporal discrepancy between content data and respective control data is predominantly the prescribed duration threshold (delay Δ₀, reference 9720, FIG. 97 , FIG. 113 ).

FIG. 114 illustrates representations 11400 of transfer delays of the configurations of FIG. 82 , FIG. 83 , and FIG. 112 , respectively, used for determining the temporal discrepancy between content data and corresponding control data, which is the duration of a moving time window during which content data is held at the circular content buffer of the high-capacity view adaptor.

For the configuration of FIG. 82 , the temporal discrepancy is Δ₀=(κ_(min)×ν×f_(t)).

For the configuration of FIG. 83 , the temporal discrepancy is (Δ₁+Δ₀+Δ₃−Δ₂).

For the configuration of FIG. 112 , the temporal discrepancy is (Δ₀+Δ₃−Δ₄)≈Δ₀.

As defined earlier, Δ₁ represents transfer delay along a path from the panoramic signal source to the first acquisition module, Δ₂ represents transfer delay along a path from the panoramic signal source to the second acquisition module, Δ₃ represents transfer delay along a path from the content controller to the view adaptor, and Δ₄ represents transfer delay along a path from the repeater to the view adaptor.

Thus, the invention provides a method of video-content filtering for selective dissemination. The method comprises processes of:

-   -   (5) Acquiring, using an acquisition module 4720 (FIG. 82 ), or         acquisition modules 4720A and 4720B (FIG. 83 ), a panoramic         signal organized into frames;     -   (6) generating a display of the panoramic signal (FIG. 96 );     -   (7) measuring durations of visual fixations of a viewer of the         display based on detecting the viewer's gaze positions (FIG. 84         ); and     -   (8) for each visual fixation attaining a prescribed duration         threshold:         -   (4a) determining a respective pivotal gaze position (8460,             8472, FIG. 84 );         -   (4b) extracting a segment of the panoramic signal             corresponding to a view region surrounding the respective             pivotal gaze position (FIGS. 87, 89, 105, 106 ), and         -   (4c) transmitting the segment to an             information-dissemination facility.

A pivotal gaze position and a pivotal frame index are initialized as default values (8440, FIG. 84 ). A gaze count is initialized to equal zero (8448, FIG. 84 ). The contour of the view region follows prescribed shape and dimensions (8750, FIG. 87, 8950 , FIG. 89, 10520 . FIG. 105 , FIG. 106 ).

An acquisition module (4720, FIG. 82, 4720A, 4720B, or FIG. 83 ) receives a source signal 4712 (which is a modulated carrier of a multimedia signal) from a panoramic signal source 4710, detects a baseband signal from the source signal. and produces panoramic signal from the baseband signal. The baseband signal may be compressed and/or warped as illustrated in FIG. 4 . The acquisition module may de-compress and/or de-warp the baseband signal where necessary. Additionally, if the detected baseband signal does not include frame indices, the acquisition module inserts a cyclical frame index into the content of each frame to produce frame-indexed content data.

Generating a display of the panoramic signal comprises supplying the panoramic signal to a virtual-reality headset configured to detect gaze positions of an operator wearing the virtual-reality headset (4750, FIG. 47 , FIG. 96 ). The headset is situated at enhanced content controller 8210. Measuring the duration of a visual fixation comprises processes of detecting gaze positions at regular time intervals and counting successive adjacent detected gaze positions where a pairwise displacement of any pair of gaze-positions is within a predefined proximity threshold (8460, FIG. 84 ).

Determining a pivotal gaze position (a reference gaze position 8525A, 8525B etc., FIG. 85, 9130A, 9130B, etc., FIG. 92 ) comprises recurrently performing processes of:

-   -   (vi) detecting a current gaze position of a current frame index         (step 8450);     -   (vii) evaluating a displacement of the current gaze position         from the pivotal gaze position (step 8458); and     -   (viii) subject to establishing that the displacement exceeds a         prescribed proximity threshold, setting the pivotal gaze         position to equal the current gaze position (step 8461), the         pivotal frame index to equal the current frame index, and the         gaze count to equal 1 (step 8463;     -   (ix) subject to establishing that the displacement does not         exceed the prescribed proximity threshold, increasing the gaze         count by unity (step 8461); and     -   (x) where the gaze count equals a prescribed count threshold         extracting the segment based on the pivotal gaze position and         pivotal frame index (steps 8472, 8478, high-capacity view         adaptor 8220).

At view adaptor 8220, a view boundary of the view region surrounding the respective pivotal gaze position is computed (module 10520, FIG. 105 , FIG. 106 ). To extract a segment of the panoramic signal corresponding to a view region, contents of successive frames of the panoramic signal are cyclically supplied (1:N cyclical-access mechanism 10230) to a plurality of content-filtering units (FIG. 102 , content-filtering units 10240, buffers 10250), operating concurrently, to produce individual content-filtered frames according to the view boundary, so that each content-filtering unit processes one frame at a time. Individual content-filtering frames are cyclically concatenated (N:1 cyclical access mechanism 10260) for transmission to a designated destination.

Each content-filtering unit 10240 performs processes of retaining pixels within the view boundary of each frame of the successive frames to produce frame segments of interest. The frame segments are reframed, according to a specified frame format, to form the content-filtered frames. The content-filtered frames may be compressed prior to dissemination. The minimum number, N, of content filtering units is determined as a ratio of evaluated processing time per frame per content-filtering unit to a frame duration.

According to an implementation of a high-capacity view adaptor 8220 that is collocated with an enhanced content controller 8210, extracting frame segments comprises performing processes of:

-   -   (f) repeatedly (FIG. 110 , loop A) receiving, from the         acquisition module 4720, the frame-indexed content data of the         panoramic signal and placing the frame-indexed content data in a         circular content buffer 10010;     -   (g) repeatedly (FIG. 110 , loop B) receiving, from the enhanced         content controller 8210, a pivotal gaze position and a         respective pivotal frame index then directing the respective         pivotal frame index to both a view-region-definition module         (10520) and a memory controller of the circular content buffer;     -   (h) accessing the circular content buffer 10010 to read         respective content data corresponding to the respective frame         index;     -   (i) receiving a view-region definition from the         view-region-definition module 10520; and     -   (j) supplying the respective content data and view-region         definition to a content filter 10200.

The circular content buffer is provisioned to store frame content data extracted from the panoramic signal (4730A, 4730C, FIG. 82 , FIG. 83 ) over a moving time window spanning an integer number, ϕ, of frames determined as: ϕ=(κ_(min)×ν)+1, where κ_(min) is a prescribed threshold of visual-fixation count κ, and ν being a predefined inter-gaze number of frames. A guard time of one frame period is added.

According to another implementation of the high-capacity view adaptor 8220, where the view adaptor is distant from the enhanced content controller 8210, acquiring a panoramic signal is performed at a first acquisition module 4720A collocated with the enhanced content controller and at a second acquisition module 4720B collocated with the high-capacity view adaptor (FIG. 83 ). Each of the first acquisition module 4720A and the second acquisition module 4720B performs processes of:

-   -   (iv) receiving, from a panoramic signal source, an enhanced         source signal based on indexed frames at source (FIG. 47 ,         module 4715);     -   (v) detecting a baseband signal from the enhanced source signal;         and     -   (vi) producing a panoramic signal, from the baseband signal, the         panoramic signal being frame-indexed.

Extracting frame segments at the high-capacity view adaptor comprises performing processes of:

-   -   (g) repeatedly (FIG. 111 , Loop A) receiving, from the second         acquisition module (FIG. 83, 4720B), frame-indexed content data         and placing the frame-indexed content data in a circular content         buffer 10010;     -   (h) repeatedly (FIG. 111 , Loop C) receiving, from the enhanced         content controller 8210, a pivotal gaze position and a         respective frame index and storing the pivotal gaze position and         respective frame index in a circular control buffer 10040;     -   (i) repeatedly (FIG. 111 , Loop D) sequentially reading from the         circular control buffer 10040 a pivotal gaze position and a         respective frame index, and directing the respective frame index         to both of a view-region-definition module and a memory         controller of the circular content buffer 10010;     -   (j) accessing the circular content buffer 10010 to read         respective content data corresponding to the respective frame         index;     -   (k) receiving a view-region definition from the         view-region-definition module; and     -   (l) supplying the respective content data and view-region         definition to content filter 10200.

The circular content buffer is provisioned to store frame content data extracted from the panoramic signal over a moving time window spanning an integer number, Φ, of frames determined as:

Φ=┌(κ_(min)×ν)+((Δ₁+Δ₃−Δ₂)/f _(t))+1┐, wherein

κ_(min) is a prescribed threshold of visual-fixation count κ, ν is a predefined inter-gaze number of frames, f_(t) is a frame duration, Δ₁ is a transfer delay of the source signal from the panoramic signal source to the enhanced content controller, Δ₂ is a transfer delay of the source signal from the panoramic signal source to the high-capacity view adaptor, Δ₃ is a transfer delay of the pivotal gaze positions from the content controller to the view adaptor (FIG. 94 , FIG. 97 , FIG. 114 ).

Methods of the embodiment of the invention are performed using one or more hardware processors, executing processor-executable instructions causing the hardware processors to implement the processes described above. Computer executable instructions may be stored in processor-readable storage media such as floppy disks, hard disks, optical disks, Flash ROMS, non-volatile ROM, and RAM. A variety of processors, such as microprocessors, digital signal processors, and gate arrays, may be employed.

Systems of the embodiments of the invention may be implemented as any of a variety of suitable circuitry, such as one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware or any combinations thereof. When modules of the systems of the embodiments of the invention are implemented partially or entirely in software, the modules contain a memory device for storing software instructions in a suitable, non-transitory computer-readable storage medium, and software instructions are executed in hardware using one or more processors to perform the techniques of this disclosure.

It should be noted that methods and systems of the embodiments of the invention and data streams described above are not, in any sense, abstract or intangible. Instead, the data is necessarily presented in a digital form and stored in a physical data-storage computer-readable medium, such as an electronic memory, mass-storage device, or other physical, tangible, data-storage device and medium. It should also be noted that the currently described data-processing and data-storage methods cannot be carried out manually by a human analyst, because of the complexity and vast numbers of intermediate results generated for processing and analysis of even quite modest amounts of data. Instead, the methods described herein are necessarily carried out by electronic computing systems having processors on electronically or magnetically stored data, with the results of the data processing and data analysis digitally stored in one or more tangible, physical, data-storage devices and media.

Although specific embodiments of the invention have been described in detail, it should be understood that the described embodiments are intended to be illustrative and not restrictive. Various changes and modifications of the embodiments shown in the drawings and described in the specification may be made within the scope of the following claims without departing from the scope of the invention in its broader aspect. 

1. A method of video-content filtering for selective dissemination comprising: acquiring a panoramic signal organized into indexed frames; generating a display of the panoramic signal; initializing a pivotal gaze position and a pivotal frame index as default values, and a gaze count to equal zero; detecting gaze positions at regular time intervals; measuring durations of visual fixations of a viewer of the display based on detecting the viewer's gaze positions; for each visual fixation attaining a prescribed duration threshold: determining a respective pivotal gaze position; extracting a segment of the panoramic signal corresponding to a view region, of prescribed shape and dimensions, surrounding the respective pivotal gaze position; and transmitting said segment to an information-dissemination facility.
 2. The method of claim 1 wherein said acquiring comprises performing, at an acquisition module, processes of: receiving a source signal from a panoramic signal source; detecting a baseband signal from the source signal; and producing said panoramic signal from the baseband signal.
 3. The method of claim 2 wherein said acquiring comprises one of: determining indices of individual frames from said baseband signal, subject to an indication that said source signal contains frame indices; and inserting a cyclical frame index into content of each frame to produce said frame-indexed frames.
 4. The method of claim 2 wherein said generating comprises supplying said panoramic signal to a virtual-reality headset, at a content controller, configured to detect gaze positions of an operator wearing the virtual-reality headset.
 5. The method of claim 1 wherein said measuring comprises counting successive adjacent detected gaze positions where pairwise displacement of any pair of gaze-positions is within a predefined proximity threshold.
 6. The method of claim 1 wherein said determining comprises recurrently performing processes of: detecting a current gaze position at a current frame index; evaluating a displacement of the current gaze position from the pivotal gaze position; subject to establishing that the displacement exceeds a prescribed proximity threshold, setting: the pivotal gaze position to equal the current gaze position; the pivotal frame index to equal the current frame index; and the gaze count to equal 1; subject to establishing that the displacement does not exceed the prescribed proximity threshold, increasing the gaze count by unity; and where the gaze count equals a prescribed count performing said extracting based on said pivotal gaze position and pivotal frame index.
 7. The method of claim 1 further comprising defining, at a view adaptor, a view boundary of said view region surrounding said respective pivotal gaze position.
 8. The method of claim 7 wherein said extracting comprises: cyclically supplying contents of successive frames of said panoramic signal to a plurality of content-filtering units operating concurrently, to produce individual content-filtered frames according to said view boundary, so that each content-filtering unit processes one frame at a time; and cyclically concatenating said individual content-filtering frames for transmission.
 9. The method of claim 8 wherein each said content-filtering unit performs processes of: retaining pixels within said view boundary of each frame of said successive frames to produce frame segments of interest; reframing said frame segments according to a specified frame format; and optionally, compressing said content-filtered frames.
 10. The method of claim 8 wherein the plurality of content-filtering units comprises at least a number, N, of content filtering units, determined as a ratio of evaluated processing time per frame per content-filtering unit to a frame duration.
 11. The method of claim 4 wherein said extracting comprises performing, at a view adaptor collocated with the content controller, processes of: repeatedly: receiving, from said acquisition module, frame-indexed content data; and placing said frame-indexed content data in a circular content buffer; repeatedly: receiving, from said content controller, a pivotal gaze position and a respective pivotal frame index; and directing said respective pivotal frame index to a view-region-definition module and a memory controller of said circular content buffer; accessing said circular content buffer to read respective content data corresponding to said respective frame index; receiving a view-region definition from the view-region-definition module; and supplying said respective content data and view-region definition to a content filter.
 12. The method of claim 11 further comprising provisioning said circular content buffer to store frame content data extracted from the panoramic signal over a moving time window spanning an integer number, ϕ, of frames determined as: ϕ=(κ_(min)×ν)+1, κ_(min) being a prescribed threshold of visual-fixation count κ, and ν being a predefined inter-gaze number of frames.
 13. The method of claim 1 wherein said acquiring comprises performing at each of a first acquisition module collocated with a content controller and a second acquisition module collocated with a view adaptor, processes of: receiving a source signal from a panoramic signal source; detecting a baseband signal from the source signal; and producing said panoramic signal, from the baseband signal, said panoramic signal comprising frame-indexed content indexed as source.
 14. The method of claim 13 wherein said extracting comprises performing, at a view adaptor, processes of: repeatedly: receiving, from said second acquisition module, frame-indexed content data; and placing said frame-indexed content data in a circular content buffer; repeatedly: receiving, from said content controller, a pivotal gaze position and a respective frame index; and storing said pivotal gaze position and respective frame index in a circular control buffer; repeatedly: sequentially reading stored pivotal gaze position and a respective frame index from said circular control buffer; and directing said respective frame index to a view-region-definition module and a memory controller of said circular content buffer; accessing said circular content buffer to read respective content data corresponding to said respective frame index; receiving a view-region definition from the view-region-definition module; and supplying said respective content data and view-region definition to a content filter.
 15. The method of claim 14 further comprising provisioning said circular content buffer to store frame content data extracted from the panoramic signal over a moving time window spanning an integer number, Φ, of frames, where: Φ=┌(κ_(min)×ν)+((Δ₁+Δ₃−Δ₂)/f _(t))+1┐, wherein κ_(min) is a prescribed threshold of visual-fixation count κ, ν is a predefined inter-gaze number of frames, f_(t) is a frame duration, Δ₁ is a transfer delay of said source signal from the panoramic signal source to the content controller, Δ₂ is a transfer delay of said source signal from the panoramic signal source to the view adaptor, Δ₃ is a transfer delay of said pivotal gaze positions from the content controller to the view adaptor.
 16. An apparatus for content-filtering of video signals comprising: an acquisition module configured to receive a modulated carrier from a panoramic signal source and generate a baseband panoramic signal organized into indexed frames; a content controller comprising: a device for producing a panoramic display of the baseband panoramic signal; and a refresh module configured to measure durations of visual fixations of a viewer of the panoramic display, based on detecting the viewer's gaze positions, and determine a pivotal gaze position and a respective pivotal frame index for each visual fixation attaining a prescribed duration threshold; and a view adaptor comprising: a module for computing a boundary of a view region, of prescribed shape and dimensions, surrounding said pivotal gaze position; and an array of content-filtering units operating concurrently to extract segments, corresponding to the view region, of specific frames of the baseband panoramic signal starting with a frame of said respective pivotal frame index and ending upon determining a new pivotal frame index of a subsequent pivotal gaze position.
 17. The apparatus of claim 16 wherein each said content-filtering unit is configured to reframe said segments according to a specified frame format to produce filtered frames; and optionally, compress said filtered frames.
 18. The apparatus of claim 17 further comprising: a circular content buffer holding content data of the baseband panoramic signal over a moving time window spanning a predefined number of frame periods; a first cyclical-access mechanism for sequentially transferring said specific frames of the baseband panoramic signal to individual content-filtering units of the array of content-filtering units; and a second cyclical-access mechanism for sequentially transferring said filtered frames to a respective destination.
 19. The apparatus of claim 18 wherein said circular content buffer is provisioned to store frame content data extracted from the baseband panoramic signal over a moving time window spanning an integer number, ϕ, of frames determined as: ϕ=(κ_(min)×ν)+1, wherein: κ_(min) is a count of successive adjacent gaze positions within said prescribed duration threshold, where pairwise displacement of any pair of gaze-positions is within a predefined proximity threshold; and ν is a predefined inter-gaze number of frames.
 20. A system for content-filtering of video signals comprising: a first acquisition module configured to receive a modulated carrier from a panoramic signal source and generate a baseband panoramic signal organized into indexed frames; a content controller, collocated with the first acquisition module, comprising: a device for producing a panoramic display of the baseband panoramic signal; and a refresh module configured to measure durations of visual fixations of a viewer of the panoramic display, based on detecting the viewer's gaze positions, and determine a pivotal gaze position and a respective pivotal frame index for each visual fixation attaining a prescribed duration threshold; a repeater for retransmitting the modulated carrier received at the first acquisition module to a second acquisition module configured to generate a replica of said baseband panoramic signal; and a view adaptor comprising: a module for computing a boundary of a view region, of prescribed shape and dimensions, surrounding said pivotal gaze position; and an array of content-filtering units operating concurrently to extract segments, corresponding to the view region, of specific frames of the replica of said baseband panoramic signal starting with a frame of said respective pivotal frame index and ending upon determining a new pivotal frame index of a subsequent pivotal gaze position.
 21. The system of claim 20 wherein each said content-filtering unit is configured to reframe segments according to a specified frame format to produce filtered frames; and optionally, compress said filtered frames.
 22. The system of claim 21 further comprising: a circular content buffer holding content data of the replica of the baseband panoramic signal over a moving time window spanning a predefined number of frame periods; a first cyclical-access mechanism for sequentially transferring said specific frames of the baseband panoramic signal to individual content-filtering units of the array of content-filtering units; and a second cyclical-access mechanism for sequentially transferring said filtered frames to a respective destination.
 23. The system of claim 22 wherein said circular content buffer is provisioned to store frame content data extracted from the baseband panoramic signal over a moving time window spanning an integer number, ϕ*, of frames determined as: ϕ*=┌(κ_(min)×ν)+((Δ₁+Δ₃−Δ₂)/f _(t))+1┐, wherein: κ_(min) is a count of successive adjacent gaze positions within said prescribed duration threshold, where pairwise displacement of any pair of gaze-positions is within a predefined proximity threshold; ν is a predefined inter-gaze number of frames, f_(t) is a frame duration, Δ₃ is a transfer delay of said pivotal gaze positions from the content controller to the view adaptor, and Δ₄ is a transfer delay from said repeater to the view adaptor. 